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© 2003 American Institute of Physics. The authors wish to thank D. C. Look, H. Morkoc¸ and J. van Nostrand for providing the investigated material. C. D.-G. acknowledges M. E. C. D. for a postdoctoral research grant. This work has been partially supported by MCYT through Project No. MAT2000-2119., Time-resolved cathodoluminescence (TRCL) and photocurrent (PC) spectroscopies have been applied to the study of the yellow band of Si-doped GaN. Measurements carried out combining both techniques unambiguously reveal the complex nature of this broad emission and confirm that different deep defect levels are involved in the observed luminescence. Five emission bands centered at 1.89, 2.03, 2.16, 2.29, and 2.38 eV were found by steady state and time-resolved CL investigations, while PC spectra showed four transitions at about 2.01, 2.14, 2.28, and 2.43 eV. The behavior of the deep-level emissions intensity as a function of the excitation pulse width as well as their decay times were investigated by TRCL. A decay time of 245 mus was measured for the 2.29 eV emission band, while longer decay times of 315 and 340 mus were found, respectively, for the 2.16 and 2.38 eV bands, in agreement with TRCL spectra. The appearance of the 2.03, 2.16, 2.29 eV and 2.38-2.43 eV peaks both in PC and CL spectra suggests that these bands are related to deep acceptor to band transitions, as supported by the single exponential character of the corresponding decay transients., MCYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors acknowledge C.A.I. de Implantación Iónica (U.C.M.) for technical support, and especially to Rosa Cimas Cuevas for aid in sample processing, and C.A.I. de Espectroscopia (U.C.M.) for providing access to the FTIR spectrometer. This work was partially supported by the Spanish CICYT, under Contract No. TIC 01-1253., The composition, bonding configuration, hydrogen content, and paramagnetic defects of SiOxHy thin films were studied. Films were deposited by the electron cyclotron resonance plasma method at room temperature using SiH4 and O-2 as precursor gases. The film composition was measured by heavy ion elastic recoil detection analysis and energy dispersive x-ray spectroscopy. Suboxide films with compositions ranging from SiO2 to SiH0.38 were obtained. Infrared spectroscopy showed the presence of different Si-O and Si-H vibration modes. The usual estimation of the oxygen to silicon ratio by the wave number of the Si-O-Si stretching band was not accurate for films far from stoichiometry. These off-stoichiometric films also showed a broader Si-O-Si stretching peak than the stoichiometric ones, indicating a higher bonding disorder. The position of the Si-O-Si bending and rocking modes did not depend on the film composition. On the other hand, the peak position of the Si-H modes were found strongly dependent on the Si environment. By single-wavelength ellipsometry at lambda=632.8 nm the refractive index n was found to range between 1.45 (SiO2) and 2.04 (SiO0.06H0.36). Electron spin resonance measurements showed that stoichiometric films presented the well known E' center (.Siequivalent toO(3)) with concentrations in the 10(16)-10(17) cm(-3) range, while for Si-rich films (x<1) the Si dangling bond center (Si-DB, .Siequivalent toSi(3)) was the only detectable defect, with concentrations in the 10(18)-10(19) cm(-3) range. In near-stoichiometric films both E-' and Si-DB centers were found., Spanish CICYT, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 1996 American Institute of Physics. This work has been supported by DGICYT (Projects Nos. PB-93-1256 and HP94-098)., Planarization of large grain diamond films has been induced by 193 nm excimer laser irradiation. Secondary emission images and cathodoluminescence (CL) in the scanning electron microscope have been used to characterize-the irradiated area. Irradiation causes changes in the structure of defects involving nitrogen and vacancies. Evolution of the CL signal with the number of pulses indicates that the luminescence intensity tends to stabilize when a smooth film surface is obtained., DGICYT (Spain), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2000 American Institute of Physics. The authors thank Professor Piqueras for helpful discussions. A. Cremades thanks the Spanish Ministerio de Educación y Cultura for a postdoctoral grant. This work was supported by the Bayerische Forschungsstiftung (FOROPTO II)., Combined electron beam induced current and transmission electron microscopy (TEM) measurements have been performed on both undoped and Si-doped AlGaN epitaxial films with aluminum contents x ranging from x = 0 to x = 0.79, in order to correlate the electrical and structural properties of the films. The diffusion length of holes in the films ranges between 0.3 and 15.9 mu m, and the estimated lifetime of holes for doped samples varies between 0.2 ns and 16 mu s. Different effects contribute to the observed increase in the diffusion length with increasing aluminum content. Among others, dislocations seem to be active as nonradiative recombination sites, and phase separation and decomposition as observed by TEM in Al-rich alloys lead to the formation of a spatially indirect recombination path due to the piezoelectric field in the films. Potential fluctuations associated with these phase irregularities could also give rise to electron induced persistent conductivity contributing to the increase of the diffusion length. From our experimental observations, we conclude that the silicon dopants are partially activated in Al-rich alloys, and do not influence significantly the values of the diffusion length of holes in these samples., Bayerische Forschungsstiftung (FOROPTO II), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

European Vacuum Conference (EVC-7) (7. 2001. Madrid) European Topical Conference on Hard Coatings (ETCHC-3) (3. 2001. Madrid). © 2002 Elsevier Science Ltd. All rights reserved. The authors acknowledge C.A.I. de Implantación Iónica (U.C.M.) for technical support and C.A.I. de Espectroscopía(U.C.M.) for the availability of the FTIR spectrometer. This work was partially supported by the Spanish CICYT, under grant TIC 2001-1253., The bonding configuration, hydrogen evolution and defect content of rapid thermally annealed (RTA) SiOx:H films of different initial compositions were studied. Infrared absorption measurements showed that all the hydrogen present in the films was lost at temperatures lower than 700degreesC without any change in the oxygen to silicon ratio of films. RTA temperatures higher than 700degreesC promote a change in the Si-O-Si stretching position from the initial unannealed value to the 1070-1080 cm(-1) range independent of the initial film composition. Electron Spin Resonance (ESR) measurements show that all the films contained two types of paramagnetic defects: E' (.SidropO(3)) and D (.SidropSi(3))Annealing up to 700degreesC promotes the disappearance of the E' centre. For films where the D defect is present (all except the film with x approximate to 2), the concentration of these defects initially decreases for annealing temperatures of 400degreesC, then continuously increases for temperatures up to 700degreesC, getting a saturation value in the 10(18)-10(19) cm(-3) range for higher temperatures. ESR characterisation suggests that annealing at higher temperatures promotes the formation of a high-quality SiO2 matrix in which Si nanocrystals are formed, the D defects being located within these nanocrystals., Spanish CICYT, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© IOP Publishing Ltd. The authors would like to thank CAI de Implantación Iónica from the Complutense University in Madrid for technical assistance with the ECR-CVD system. This research was partially supported by the Spanish Government under Grant No TIC 98/0740., The influence of the semiconductor doping type over the electrical properties of Al/SiNx :H/In0.53Ga0.47As metal-insulator-semiconductor (MIS) devices has been studied using capacitance-voltage (C-V) and current-voltage (I-V) measurements. The C-V data show that the SiNx:H/p-In0.53Ga0.47As interface is more defective than the SiNx,:H/n-In0.53Ga0.47As one. In both n- and p-type MIS structures, the interface trap density (D-it), the electrical breakdown field (E-B) and the resistivity (rho) are highly dependent on the insulator composition. On the other hand, rapid thermal annealing treatments at temperatures up to 600 degrees C induce a gradual improvement of both interface and SINx:H bulk quality on n-type MIS devices, whereas a continuous degradation of the SiNx:H/p-In0.53Ga0.47As interface properties is observed. Zinc out-diffusion from p-In0.53Ga0.47As towards the insulator-semiconductor interface could explain the poorest electrical characteristics of the MIS structures based on a p-type semiconductor., Spanish Government, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 IOP Publishing Ltd. The authors would like to thank B Steudel (Hahn-Meitner-Institut) for her inestimable help in the C–V measurements. C.A.I. de Implantación Iónica (UCM) is acknowledged for the availability of the deposition system and RTA furnace. This work has been partially financed by the CICYT (Spain) under contract no. TIC 01-1253., We have studied and compared the effects of conventional annealing in a forming gas atmosphere (430 degreesC, 20 min) and rapid thermal annealing (RTA) in an inert Ar atmosphere (400-1000 degreesC, 30 s) on Al/SiOxNyHz/Si devices. The samples were deposited by the electron cyclotron resonance plasma method at low temperature (T = 200 degreesC). The devices were characterized by surface photovoltage measurements before applying contacts and by capacitance-voltage measurements. All the as-deposited samples containing N had positive flat-band voltage, which corresponds to negative charge in the insulator and/or in the interface states (Q(INS)). Additionally, trapping of positive charge is observed when measuring from inversion to accumulation after measuring from accumulation to inversion. This behaviour is tentatively attributed to the presence of defects related to N, such as the K centre (N-3=Siup arrow) or the N dangling bond (Si-2=Nup arrow), which may be present in a negatively charged state. For samples of SiO2 composition, with a negligible N content, Q(INS) is positive. High densities of interface states (D-it), above 10(12) eV(-1) cm(-2), are observed in the as-deposited samples. Both the annealing in a forming gas atmosphere and the RTA result in the change of the sign of Q(INS) from negative to positive and a decrease of its absolute value, as well as a decrease of D-it of about one order of magnitude. The trapping of positive charge is also greatly reduced. These improvements of the electrical properties are attributed to the passivation of defects by H present in the forming gas atmosphere or in the SiOxNyHz film itself in a non-bonded state. For RTA temperatures above 700 degreesC the properties of the devices degrade due to the release of H. The combination of RTA and annealing in a forming gas atmosphere results in the best properties., CICYT (Spain), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 American Institute of Physics. The authors wish to express our gratitude to Dr. W. Bohne, Dr. J. Röhrich, and Dr. B. Selle, from the Hahn-Meitner-Institut in Berlin, for a long friendship and fruitful collaboration, from which the HIERDA results presented in this work are only a small part. They also thank the financial support of the Spanish National Office for Science and Technology under Grant No. TIC98/0740 and the technical assistance received from the ion implantation facility “CAI-Implantación Iónica” of the University of Madrid., Bulk properties of SiNx:H thin film dielectrics and interface characteristics of SiNx:H/Si devices are studied by a combination of electrical measurements (capacitance-voltage and current-voltage characteristics) and defect spectroscopy (electron spin resonance). The SiNx:H films were deposited by an electron cyclotron resonance plasma method and subjected to rapid thermal annealing postdeposition treatments at temperatures between 300 and 1050 degreesC for 30 s. It is found that the response of the dielectric to the thermal treatments is strongly affected by its nitrogen to silicon ratio (N/Si=x) being above or below the percolation threshold of the Si-Si bonds in the SiNx:H lattice, and by the amount and distribution of the hydrogen content. The density of Si dangling bond defects decreases at moderate annealing temperatures (below 600 degreesC) in one order of magnitude for the compositions above the percolation threshold (nitrogen rich, x=1.55, and near stoichiometric, x=1.43). For the nitrogen rich films, a good correlation exists between the Si dangling bond density and the interface trap density, obtained from the capacitance measurements. This suggests that the observed behavior is mainly determined by the removal of states from the band tails associated to Si-Si weak bonds, because of the thermal relaxation of the bonding strain. At higher annealing temperatures the deterioration of the electrical properties and the increase of the Si dangling bonds seem to be associated with a release of trapped hydrogen from microvoids of the structure. For the silicon rich samples rigidity percolates in the network resulting in a rigid and strained structure for which the degradation phenomena starts at lower temperatures than for the other two types of samples., Spanish National Office for Science and Technology, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2002 IOP Publishing Ltd. This work was partially supported by the Spanish Government under Grant No TIC98/0740., In this paper we report on the optimization of the SiNchi:H insulator, deposited by the electron cyclotron resonance (ECR) plasma method, as a dielectric for metal-insulator-semiconductor (MIS) structures built on an InP compound semiconductor. Two different MIS structures have been obtained in which the minimum of the interface trap density (D-it,D-min) at the insulator/InP interface attains values of device quality. In the first structure, a Al/SiN1.5:H/SiN1.6:H/InP dual-layer insulator was obtained and optimized after rapid thermal annealing treatment at 500 degreesC for 30s. After this treatment, the value of D-it,D-min was 9 x 10(11) cm(-2) eV(-1). In the second structure, the MIS structure was Al/SiN1.6:H/InP single-layer insulator, in which the InP surface was exposed to an N-2 plasma prior to the SiN1.6:H film deposition. In this case, the value of D-it.min was 1.6 x 10(12) cm(-2) eV(-1). Both types of structures were used as gate insulators on N-channel enhanced-mode MIS field-effect transistor test devices. From the dc output characteristics of the transistors, we obtain values for the electron channel mobility in the range 1550-1600 cm(-2) V-1 s(-1). This is a confirmation of the great potential of the ECR plasma method as a simple way to obtain device quality gate structures on InP without the use of passivation processes of the InP surface prior to the deposition of the gate dielectric, thus simplifying the whole device fabrication procedure., Spanish Government, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© IOP Publishing Ltd. The authors would like to thank E. Iborra for the facilities for the infrared characterization of films. This research was partially supported by the Spanish CYCIT under grant No TIC 93/0175., SiNx:H thin films were deposited by the electron cyclotron resonance plasma method at low substrate temperature (200 degrees C) to fabricate metal-insulator-semiconductor devices. The effects of film properties on the electrical characteristics of two different devices, SiNx:H/Si and SiNx:H/InP, were analysed according to the C-V high-low frequency method. The results show that, in the devices based on Si, the presence of N-H bonds in the SiNx:H film increases the density of trapping centres at the insulator/semiconductor interface. This behaviour was analysed by the model recently proposed by Ying (1995 J. Vac. Sci. Technol. B 13 1613) for nitrided SiO2/Si interfaces. For the SiNx:H/InP capacitors, the electrical characteristics of the interface were strongly dependent on the SiNx:H composition. When the nitrogen to silicon ratio of the film was N/Si = 1.49, the minimum of the interface trap density was 2 x 10(12) cm(-2) eV(-1) This value was similar to the same data reported by other authors on devices where the InP surface was sulphur passivated. This suggests that nitrogen atoms of the insulator play some passivation role at the InP surface. The plasma exposure of the semiconductor surface during the deposition of the SiNx:H film promotes the formation of phosphorus vacancies at the InP surface. Nitrogen atoms may fill these vacancies and this gives rise to an insulator/semiconductor interface with few defects., Spanish (CICYT), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© American Institute of Physics. This research was partially supported by the Spanish Government (CICYT), under Grant no. TIC 93/0175., We have obtained Al/SiNx:H/InP metal-insulator-semiconductor devices depositing SiNx:H thin films by the electron cyclotron resonance plasma method at 200 degrees C. The electrical properties of the structures were analyzed according to capacitance-voltage and deep level transient spectroscopy measurements. We deduce an inverse correlation between the insulator composition-the N/Si ratio-and the density of interface traps: those films with the maximum N/Si ratio (1.49) produce devices with the minimum trap density-2 x 10(12) cm(-2) eV(-1) at 0.42 eV. above the midgap. We explain the influence of film composition on the interface trap density in terms of a substitution of phosphorous vacancies at the InP surface, V-p, by N atoms coming from the insulator, N-Vp. The values obtained in our research for the interface trap distribution were similar to other published results for devices that use chemical and/or physical passivation processes of the InP surface prior to the deposition of the insulator., Spanish Government (CICYT), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 IOP Publishing Ltd. We wish to thank the financial support of the Spanish National Office for Science and Technology under grant no TIC98-0740 and the technical assistance of the ion implantation center ‘CAI-Implantación Iónica’ of the University of Madrid., A comparative investigation of the characteristics of the SiNx:H/Si interface has been undertaken by capacitance-voltage measurements and surface photovoltage spectroscopy. By each of these techniques, we have determined the distribution of the interface trap density within the silicon bandgap. The samples were grown by the electron-cyclotron resonance plasma method starting from SiH4 and N-2 as precursor gases whose flow ratio was varied to produce films of three different compositions: silicon rich, near stoichiometric and nitrogen rich. Post-deposition rapid thermal annealing treatments were applied to observe the evolution of interface properties with the annealing temperature in the range from 300 to 1050 degreesC. For thin dielectrics, the interface state density has a U-shaped distribution dominated by hand-tail states. The minimum of this distribution decreases significantly and shifts to midgap for moderate annealing temperatures. For higher annealing temperatures, the trend is reversed. In the silicon-rich films, the percolation of rigidity caused by the chains of Si-Si bonds impedes the initial decrease of the defect density. For thicker films, the strain of the: SiNx:H film produces a higher density of defects that results in increased levels of leakage currents and poorer electrical characteristics., Spanish National Office for Science and Technology, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

European Vacuum Conference (EVC 5) / International Conference on Thin Films (ICTF 10) (5th / 10th. 1996. Salamanca, Spain). (C) Elsevier Science SA., The influence of the gas flow ratio (R) (O-2/SiH4 and N-2/SiH4) and the deposition temperature on the physical properties of SiOy and SiNx:H thin films deposited by the ECR-CVD method is analyzed. Two deposition regimes limited by R = 1, are found for SiOy films. At R < 1, films are very Si-rich in nature, with [O]/[Si] ratios as low as 0.55. At R > 1, the [O]/[Si] ratio varies between 1.69 and 1.88 and the full width at half maximum of the Si-O stretching peak is almost kept constant at 90 cm(-1). The effect of increasing substrate temperatures is mainly to promote a nearest stoichiometric character of the films. The two deposition regimes described agree with the optical diagnosis of the discharge, that present Si related species in those created at R < 1, and OH and O-2(+) species in those created at R > I. A similar trend is observed for the deposition of SiNx:H films, for which the limiting gas flow ratio is also R = I. At R < 1, the films are very Si-rich (x less than or equal to 0.38), meanwhile at R > 1, the composition corresponds to near stoichiometric and N-rich films (x = 0.91-1.49). The main effect of the substrate temperature is to reduce the hydrogen content of the films. Both SiOy and SINx:H films are used in Si-based MIS structures, for those the minimum density of interface states is 3 X 10(11) cm(-2) eV(-1)., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

International Vacuum Congress (14. 1999. Birmingham, Inglaterra )/ International Conference on Solid Surfaces (10. 1999. Birmingham, Inglaterra) / International Conference on Nanometre-Scale Science and Technology (5. 1999. Birmingham, Inglaterra) / International Conference on Quantitative Surface Analysis. (10. 1999. Birmingham,Inglaterra). © EIsevier Science SA., We have analyzed the influence of rapid thermal annealing (from 300 to 1050 degrees C) on the optical properties of a-SiN(x):H. Three compositions were investigated: x = 0.97, x = 1.43 and x = 1.55. Two different behaviors are observed depending on whether the as-grown nitrogen to silicon ratio of the samples is above or below the percolation threshold (x = 1.1) of Si-Si bonds, in the matrix of silicon nitride. The samples with x: = 1.43 and 1.55 experience an increase of the Tauc coefficient (B) and a decrease of the Urbach parameter (E(0)) at low annealing temperatures. while at high temperatures the trend is inverted. On the contrary, the samples with x = 0.97 show a slight and continuous increase of B and a similar decrease of E(0). The different behavior of the films with x < 1.1 is explained by the percolation of the Si-Si bonds, which maintains the order of the structure at high annealing temperatures, preventing the inversion of the trends of B and E(0)., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© i996 Elsevier Science S.A.. The authors wish to tank Dr J.J. Schermer and Dr G.Jansen for the loan of the samples. Mr A.J. Fernandes is acknowledged for his help in the Raman measurements. This work has been partially supported by DGICYT project numbers PB93-1256 and HP95-98B., Flame grown diamond films on a molibdenium substrate are characterised by cathodoluminescence (CL), photoluminescence (PL), micro-Raman and scanning electron microscopy in the emissive mode. Different crystal habit regions grow with an annular symmetry. A correlation between morphology, CL, PL and Raman measurements is obtained for each region. The influence of the growth parameters is discussed., DGICYT (Spain), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2010 American Institute of Physics. The study was partially supported by the local government Junta de Castilla y León under Grant No. VA018A06, and by the Spanish TEC2007 under Grant No. 63318 and TEC2008 under Grant No. 06988-C02-O2., The influence of the silicon nitride blocking layer thickness on the interface state densities (D(it)) of HfO(2)/SiN(x):H gate-stacks on n-type silicon have been analyzed. The blocking layer consisted of 3 to 7 nm thick silicon nitride films directly grown on the silicon substrates by electron-cyclotron-resonance assisted chemical-vapor-deposition. Afterwards, 12 nm thick hafnium oxide films were deposited by high-pressure reactive sputtering. Interface state densities were determined by deep-level transient spectroscopy (DLTS) and by the high and low frequency capacitance-voltage (HLCV) method. The HLCV measurements provide interface trap densities in the range of 10(11) cm(-2) eV(-1) for all the samples. However, a significant increase in about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride barrier layers. In this work we probe that this increase is an artifact due to the effect of traps located at the internal interface existing between the HfO(2) and SiN(x):H films. Because charge trapping and discharging are tunneling assisted, these traps are more easily charged or discharged as lower the distance from this interface to the substrate, that is, as thinner the SiN(x):H blocking layer. The trapping/detrapping mechanisms increase the amplitude of the capacitance transient and, in consequence, the DLTS signal that have contributions not only from the insulator/substrate interface states but also from the HfO(2)/SiN(x):H interlayer traps., Junta de Castilla y León, Spanish TEC2007, Spanish TEC2008, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors gratefully acknowledge Dr. M. N. Blanco and Dr. E. Redondo for the fruitful collaboration with them in recent years. They also wish to express their deep gratitude to Dr. B. Selle, Dr. I Sieber, Dr. W. Bohne, Dr. J. Röhrich, Dr. Kliefoth, Dr. W. Füssel, and in general, to the people of the Hahn-Meitner Institut in Berlin, for a long friendship and fruitful collaboration. Thanks are also due to Professor F. López and Professor D. Bravo (Materials Department, Autónoma University of Madrid) for ESR measurements. Last, but no least, technical assistance received from the people of the ion implantation facility (CAI—Implantación Iónica) of the Complutense University of Madrid (P. Fernández and R. Cimas) is greatly acknowledge. The financial support of this work was partially done by the Spanish National Office for Science and Technology under Grant Nos. TIC 98-0740 and TIC 2001-1253., We present in this article a comprehensive study of rapid thermal annealing (RTA) effects on the physical properties of SiNx:H thin films deposited by the electron cyclotron resonance plasma method. Films of different as-deposited compositions (defined in this article as the nitrogen to silicon ratio, x=N/Si) were analyzed: from Si-rich (x=0.97) to N-rich (x=1.6) films. The evolution of the composition, bonding configuration, and paramagnetic defects with the annealing temperature are explained by means of different network bond reactions that take place depending on the as-deposited film composition. All the analyzed films release hydrogen, while Si-rich and near-stoichiometric (x=1.43) ones also lose nitrogen upon annealing. These films were used to make Al/SiNx:H/semiconductor devices with Si, In0.53Ga0.47As, and InP. After RTA treatments, the electrical properties of the three different SiNx:H/semiconductor interfaces can be explained, noting the microstructural modifications that SiNx:H experiences upon annealing., Spanish National Office for Science and Technology, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 1999 WILEY-VCH Verlag Berlin GmbH, Fed. Rep. of Germany. International Conference on Nitride Semiconductors (3. 1999. Montpellier, Francia)., We analyse the recombination and scattering at dislocations in Si doped AlGaN layers by transmission electron microscopy (TEM), electron beam induced current (EBIC) and cathodoluminescence. We show that c-type screw dislocations are nonradiative recombination centres. From temperature dependent measurements of the EBIC contrast we find a shallow acceptor state 20 meV above the valence band. The level can be understood iri terms of one-dimensional dislocation bands split off by the dislocation deformation field. In addition piezoelectric potentials play a role., Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© American Institute of Physics. The authors are indebted to Dr. J. Cárabe and Dr. J. Gandía from the National Center for Energy Research (CIEMAT) for the use of the spectrometer facility, licensing of their useful software GRAFO for optical analysis, and many helpful discussions. Their friendship and support are greatly appreciated, as well as those of the technical center CAI Implantación Iónica of the University of Madrid and the financing from the Science Ministry of Spain under contract TIC98-0740., We analyze the effect of thermal processes on the optical properties (refractive index, optical gap, Tauc coefficient, and Urbach energy) of SiNx:H films. Films with three different nitrogen to silicon ratios (x = 0.97, x = 1.43, and x = 1.55, respectively) were deposited by a chemical vapor deposition technique assisted by an electron cyclotron resonance generated plasma. After deposition they were subjected to rapid thermal annealing at temperatures ranging from 300 degrees C to 1050 degrees C. We found that the percolation threshold for Si-Si bonds (at x = 1.1) separates films with different response to thermal treatments. The changes of the Tauc coefficient and the Urbach energy at moderate annealing temperatures indicate a structural relaxation of the network for the films with x above the percolation threshold, while at higher temperatures the trends are inverted. In the case of x below the percolation limit the inversion point is not observed. These trends are well correlated with the width of the Si-N infrared stretching absorption band. Additionally the samples with as-grown x = 1.43 show a good correlation between the Urbach energy and the density of unpaired spins in silicon dangling bonds. (C) 1999 American Institute of Physics. [S0021-8979(99)08016-0]., Science Ministry of Spain, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© Elsevier Science Ireland Ltd. The authors like to thank J. Messarosch, G. Fehlauer, H. Baumgärtner, F. Kaesen, H. Geiger, V.R. Rao and T. Pompl for their assistance in electrical measurements, sample preparation and fruitful discussions. The expertise of J. Ramm, E. Beck and R. Slepicka of Balzers AG is greatfully acknowledged. This work was supported by the BMBF under grant no. BA-672. One of the authors, A. Strass, likes to thank the German Academic Exchange Service (DAAD) for financial assistance during his scientific stay at the Universidad de Chile., We developed and tested three MBE-compatible processes for the deposition of high-quality low-temperature silicon oxides and oxynitrides in the ultra high vacuum at substrate temperatures between room temperature and 500 degrees C, gas enhanced evaporation (GEE), plasma enhanced evaporation (PEE) and plasma enhanced oxidation (PEO). The deposited layers were thoroughly investigated and compared with respect to their electrical, optical and stoichiometrical properties by means of ellipsometry, mechanical profilometry, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering (RBS), Fourier transform infrared ((FTIR) spectroscopy, and by electrical measurements (I-V, C-V) on MOS structures. A model of the growth mechanism for each of the processes is suggested., German BMBF, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors acknowledge Centro de Asistencia a la Investigacıón (CAI) de Implantación Iónica [Universidad Complutense de Madrid (UCM)] for use of the deposition system and RTA furnace. CAI de Espectroscopia (UCM). Is acknowledged for providing the FTIR spectrometer. This work was partially financed by the CICYT (Spain) under Contract No. TIC 01-1253., The effect of rapid thermal annealing (RTA) processes on the structural properties of SiOxNyHz films was investigated. The samples were deposited by the electron cyclotron resonance plasma method, using SiH4, O-2 and N-2 as precursor gases. For SiOxNyHz films with composition close to that of SiO2, which have a very low H content, RTA induces thermal relaxation of the lattice and improvement of the structural order. For films of intermediate composition and of compositions close to SiNyHz, the main effect of RTA is the release of H at high temperatures (T>700degreesC). This H release is more significant in films containing both Si-H and N-H bonds, due to cooperative reactions between both kinds of bonds. In these films the degradation of structural order associated to H release prevails over thermal relaxation, while in those films with only N-H bonds, thermal relaxation predominates. For annealing temperatures in the 500-700degreesC range, the passivation of dangling bonds by the nonbonded H in the films and the transition from the paramagnetic state to the diamagnetic state of the K center result in a decrease of the density of paramagnetic defects. The H release observed at high annealing temperatures is accompanied by an increase of density of paramagnetic defects., CICYT (Spain), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© American Institute of Physics. The authors acknowledge C. A. I. de Implantación Iónica (U. C. M.) for technical support and C. A. I. de Espectroscopía (U. C. M.) for availability of the FTIR spectrometer. The work has been financed by the CICYT (Spain) under Contract No. TIC 98/0740., The effect of rapid thermal annealing processes on the properties of SiO2.0 and SiN1.55 films was studied. The films were deposited at room temperature from N-2 and SiH4 gas mixtures, and N-2, O-2, and SiH4 gas mixtures, respectively, using the electron cyclotron resonance technique. The films were characterized by Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance spectroscopy. According to the FTIR characterization, the SiO2.0 films show continuous stress relaxation for annealing temperatures between 600 and 1000 degrees C. The properties of the films annealed at 900-1000 degrees C are comparable to those of thermally grown ones. The density of defects shows a minimum value for annealing temperatures around 300-400 degrees C, which is tentatively attributed to the passivation of the well-known E' center Si dangling bonds due to the formation of Si-H bonds. A very low density of defects (5 x 10(16) cm(-3)) is observed over the whole annealing temperature range. For the SiN1.55 films, the highest structural order is achieved for annealing temperatures of 900 degrees C. For higher temperatures, there is a significant release of H from N-H bonds without any subsequent Si-N bond healing, which results in degradation of the structural properties of the film. A minimum in the density of defects is observed for annealing temperatures of 600 degrees C. The behavior of the density of defects is governed by the presence of non-bonded H and Si-H bonds below the IR detection limit. (C) 2000 American Institute of Physics. [S0021-8979(00)05903-X]., CICYT (Spain), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 IOP Publishing Ltd. Parts of this work were done during a research stay of one of the authors (FLM) at the ISL of the HMI with support of a mobility grant (PR2004-0426) of the Spanish Ministry of Education and Science. It was also supported by the research project TEC2004/1237 and the research grant (AP2003-4434) of the same Ministry. Special thanks are given to the ISL and to the CAI-‘Tecnologías Físicas for a long trajectory of fruitful collaboration., Thin films of hafnium oxide ( HfO2) have been grown by high pressure reactive sputtering on transparent quartz substrates ( UV- grade silica) and silicon wafers. Deposition conditions were adjusted to obtain polycrystalline as well as amorphous films. Optical properties of the films deposited on the silica substrates were investigated by transmittance and reflectance spectroscopy in the ultraviolet, visible and near infrared range. A numerical analysis method that takes into account the different surface roughness of the polycrystalline and amorphous films was applied to calculate the optical constants ( refractive index and absorption coefficient). Amorphous films were found to have a higher refractive index and a lower transparency than polycrystalline films. This is attributed to a higher density of the amorphous samples, which was confirmed by atomic density measurements performed by heavy- ion elastic recoil detection analysis. The absorption coefficient gave an excellent fit to the Tauc law ( indirect gap), which allowed a band gap value of 5.54 eV to be obtained. The structure of the films ( amorphous or polycrystalline) was found to have no significant influence on the nature of the band gap. The Tauc plots also give information about the structure of the films, because the slope of the plot ( the Tauc parameter) is related to the degree of order in the bond network. The amorphous samples had a larger value of the Tauc parameter, i. e. more order than the polycrystalline samples. This is indicative of a uniform bond network with percolation of the bond chains, in contrast to the randomly oriented polycrystalline grains separated by grain boundaries., Spanish Ministry of Education and Science, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors wish to thank D. C. Look, H. Morkoc¸, and J. van Nostrand for providing the investigated material. This work has been partially supported by MCYT through Project No. MAT2000-2119., The electronic recombination properties of Mg-doped GaN have been investigated by steady state and time-resolved cathodoluminescence (TRCL) in the scanning electron microscope, photocurrent (PC) spectroscopy, and optical beam induced current (OBIC). CL and OBIC maps reveal an inhomogeneous recombination activity in the investigated material. Deep levels giving rise to level-to-band transitions were detected by PC spectroscopy. A large PC quenching observed upon illumination with light of (2.65-2.85) eV is tentatively attributed to metastable traps within the band gap. CL spectra reveal the existence of emission bands centered at 85 K at 3.29, 3.20, 3.15, and 3.01 eV, respectively. Both time-resolved and steady-state CL measurements carried out under different excitation conditions indicate that the 3.15 and 3.01 eV emissions are likely related to donor-acceptor pair transitions. TRCL measurements also reveal different recombination kinetics for these bands and suggest that deep donors are involved in the mechanism responsible for the 3.01 eV emission., MCYT, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© American Institute of Physics. The authors would like to thank C.A.I. de Implantación Iónica from the Complutense University in Madrid for technical assistance with the ECR-CVD system. This work has been supported by the local Government Grant No. VA35/96 and by the Spanish government under Grant No. TIC 98/0740., We report a study of metal-insulator-semiconductor (MIS) structures on InP. The interfacial state density and deep levels existing in MIS structures were measured by deep level transient spectroscopy (DLTS) technique. The electrical insulator properties were measured by current-voltage techniques. MIS structures were fabricated on InP substrates by direct deposition of silicon nitride (SiNx:H) thin films by electron cyclotron resonance chemical vapor deposition. In this work, we show that interfacial state density can be diminished, without degrading electrical insulator properties, by fabricating MIS structures based on a dual layer insulator with different compositions and with different thickness. The effect of rapid thermal annealing treatment has been analyzed in detail in these samples. Interface state densities as low as 3 x 10(11) cm(-2) eV(-1) were measured by DLTS in some structures. Conductance transients caused by disorder-induced gap states have been observed and analyzed providing some information about interface width. Finally, deep levels induced in the substrate have been investigated. Three deep levels at energies of 0.19, 0.24, and 0.45 eV measured from the conduction band have been found, and their dependence on the rapid thermal annealing process has been analyzed. (C) 1999 American Institute of Physics. [S0021-8979(99)03824-4]., Valladolid local government, Spanish government, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© American Institute of Physics. The authors would like to thank E. Iborra for the facilities of the infrared characterization of the films. This work was partially supported by the Spanish Government (CICYT), under Grant TIC 93/0175., We have analyzed the electrical properties and bonding characteristics of SiNx:H thin films deposited at 200 degrees C by the electron cyclotron resonance plasma method. The films show the presence of hydrogen bonded to silicon (at the films with the ratio N/Si<1.33) or to nitrogen (for films where the ratio N/Si is higher than 1.33). In the films with the N/Si ratio of 1.38, the hydrogen content is 6 at. %. For compositions which are comprised of between N/Si=1.1 and 1.4, hydrogen concentration remains below 10 at. %. The films with N/Si=1.38 exhibited the better values of the electrical properties (resistivity, 6x10(13) Omega cm; and electric breakdown field, 3 MV/cm). We have used these films to make metal-insulator-semiconductor (MIS) devices on n-type silicon wafers. C-V measurements accomplished on the structures indicate that the interface trap density is kept in the range (3 - 5) x 10(11) cm(-2) eV(-1) for films with the N/Si ratio below 1.38. For films where the N/Si ratio is higher than 1.3, the trap density suddenly increases, following the same trend of the concentration of N-H bonds in the SiNx:H films. The results are explained on the basis of the model recently reported by Lucovsky [J. Vac. Sci. Technol. B 14, 2832 (1996)] for the electrical behavior of (oxide-nitride-oxide)/Si structures. The model is additionally supported by deep level transient spectroscopy measurements, that show the presence of silicon dangling bonds at the insulator/semiconductor interface (the so-called P-bN0 center), The concentration of these centers follows the same trend with the film composition of the interface trap density and, as a consequence, with the concentration of N-H bonds. This result further supports the N-H bonds located at the insulator/semiconductor interface which act as a precursor site to the defect generation of the type . Si=Si-3, i.e., the P-bN0 centers. A close relation between interface trap density, P-bN0 centers and N-H bond density is established, Spanish Government (CICYT), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

International Vacuum Congress (14. 1999. Birmingham, Inglaterra) / International Conference on Solid Surfaces (10. 1999. Birmingham, Inglaterra) / International Conference on Nanometre-Scale Science and Technology (5. 1999. Birmingham, Inglaterra) / International Conference on Quantitative Surface Analysis (10. 1999. Birmingham, Inglaterra). © Elsevier Science SA., Silicon oxynitride films were deposited at room temperature using the ECR-PECVD technique. Precursor gases were O(2), N(2) and SiH(4). The composition of the films can be controlled by regulating the gases flow ratio. R = (O(2) + N(2))/SiH(4) and R' = O(2)/SiH(4) have proved to be the key deposition parameters. FTIR spectroscopy, AES and ellipsometric measurements were performed in order to characterise the films. A single Si-O/Si-N stretching band is observed in the FTIR spectrum for all compositions, indicating single-phase homogeneous SiO(x)N(y) films. FWHM of the stretching band shows a maximum for the composition corresponding to the same number of Si-O and Si-N bonds. Samples cover the whole composition range from silicon nitride to silicon oxide including nitrogen-rich films, even though the gas flow ratio R " = N(2)/O(2) during deposition was small (from R " = 1.0 for SiO(1.9)N(0.04) to R " I = 6.7 for SiO(0.26)N(1.2)). Silicon oxide composition samples (SiO(2.0)) show essentially the same TR features as the thermal oxide: Si-O stretching band located at 1072 cm(-1), with a FWHM of 96 cm(-1) and a shoulder/peak ratio of 0.30, while nitrogen-rich samples (SiO(0.26)N(1.2)) show a total bonded hydrogen content below 2 x 10(22) cm(-3)., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 1999 Elsevier Science S.A. This work was partially supported by DGICYT (Project No. PB93-1256)., Diamond and diamond-like films grown by the torch flame method have been analysed by different techniques, namely scanning electron microscopy, Raman spectroscopy, electron paramagnetic resonance and catholuminescence microscopy, in order to investigate the main structural features of the different habits present in the films. A correlation between the observed crystal habits, the defect structure and the formation of diamond and/or diamond-like phases has been established. This enables a general quality assessment of the deposits and their correlation with some features usually observed in carbon films, DGICYT (Spain), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2004 American Institute of Physics. The authors acknowledge C. A. I. de Implantación Iónica (U.C.M.) for availability of the deposition system. C.A.I. of Espectroscopia (U.C.M.) is acknowledged for availability of FTIR spectrometer. The work has been partially financed by the CICYT (Spain) under Contract No. TIC 01-1253. Technical support of G. Keiler (HMI) is gratefully acknowledged., The influence of H on the composition and atomic concentrations of Si, O, and N of plasma deposited SiOxNyHz films was investigated. The bonding scheme of H was analyzed by Fourier-transform infrared spectroscopy. The composition and absolute concentrations of all the species present in the SiOxNyHz, including H, was measured by heavy-ion elastic recoil detection analysis (HI-ERDA). Samples were deposited from SiH4, O-2, and N-2 gas mixtures, with different gas flow ratios in order to obtain compositions ranging from SiNyHz to SiO2. Those samples deposited at higher SiH4 partial pressures show both Si-H and N-H bonds, while those deposited at lower SiH4 partial pressures show N-H bonds only. The Si-H and N-H bond concentrations were found to be proportional to the N concentration. The concentration of H was evaluated from the Si-H and N-H stretching absorption bands and compared to the HI-ERDA results, finding good agreement between both measurements. The deviation from H-free stoichiometric SiOxNy composition due to the presence of N-H bonds results in an effective coordination number of N to produce Si-N bonds lower than 3. By fitting the experimental composition data to a theoretical model taking into account the influence of N-H bonds, the actual concentration of N-H bonds was obtained, making evident the presence of nonbonded H. The presence of Si-H and Si-Si bonds was found to partially compensate the effect of N-H bonds, from the point of view of the relative N and Si contents. Finally, the presence of N-H bonds results in a lower Si atom concentration with respect to the stoichiometric film, due to a replacement of Si atoms by H atoms. This decrease of the Si concentration is lower in those films containing Si-H and Si-Si bonds. A model was developed to calculate the Si, O, and N atom concentrations taking into account the influence of N-H, Si-H, and Si-Si bonds, and was found to be in perfect agreement with the experimental data measured by HI-ERDA., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Institute of Physics. The authors acknowledge C. A. I. de Impalntación Iónica (U. C. M.) for availability of deposition system and Dr. E. Iborra (E. T. S. I. T. Universidad Politécnica de Madrid) for availability of FTIR spectrometer. The work has been partially financed by the CICYT (Spain) under Contract No. TIC 01-1253. Technical support of G. Keiler is gratefully acknowledged., SiOxNyHz films were deposited from O-2, N-2, and SiH4 gas mixtures at room temperature using the electron cyclotron resonance plasma method. The absolute concentrations of all the species present in the films (Si, O, N, and H) were measured with high precision by heavy-ion elastic recoil detection analysis. The composition of the films was controlled over the whole composition range by adjusting the precursor-gases flow ratio during deposition. The relative incorporation of O and N is determined by the ratio Q = phi(O-2)/(phi(SiH4) and the relative content of Si is determined by R =[phi(O-2)+phi(N-2)]/phi(SiH4) where phi(SiH4), phi(O-2), and phi(N-2) are the SiH4, O-2, and N-2 gas flows, respectively. The optical properties (infrared absorption and refractive index) and the density of paramagnetic defects were analyzed in dependence on the film composition. Single-phase homogeneous films were obtained at low SiH4 partial pressure during deposition; while those samples deposited at high SiH4 partial pressure show evidence of separation of two phases. The refractive index was controlled over the whole range between silicon nitride and silicon oxide, with values slightly lower than in stoichiometric films due to the incorporation of H, which results in a lower density of the films. The most important paramagnetic defects detected in the films were the K center and the E' center. Defects related to N were also detected in some samples. The total density of defects in SiOxNyHz films was higher than in SiO2 and lower than in silicon nitride films., CICYT (Spain), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 Elsevier Science S.A. All rights reserved. European Conference on Diamond, Diamond-Like Materials, Nitrides and Silicon Carbide (10. 199. Praga. Republica Checa). The authors wish to thank Dr. Qi Hua Fan and Mr. A.J. Fernandes for the growth facilities., The properties of microelectrical conduction in microwave plasma assisted chemical vapour deposition (MPCVD) diamond films were investigated using an atomic force microscopy probe, giving a morphological map of the electrical conduction with a spatial resolution better than 500 nm. Also, a cathodoluminescence map with a spatial resolution of about 1 mu m was obtained, giving the possibility of correlating the defects involved in the different carrier transport phenomena. Using micro-Raman analysis several bands could be identified. It is found that the defects responsible for the cathodoluminescence (CL) blue band are responsible for the major part of the electrical conduction in diamond films, while the defects localised in < 111 > surfaces, responsible for the green CL emission, could be involved in a less conductive process., Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

International Conference on Amorphous and Microcrystalline Semiconductors - Science and Technology (ICAMS 17) (17. 1997. Budapest, Hungría). © Elsevier Science BV., We have analyzed the effects of rapid thermal annealing on the composition and on the bonding and optical properties of amorphous hydrogenated silicon nitride (a-Si-x:H) thin films deposited at room temperature by the electron cyclotron resonance plasma method. Films with three different as-grown compositions have been studied, namely x = 0.97, 1.43 and 1.55, Annealing effects were related to film composition. In films with the presence of both Si-H and N-H bonds (as-grown compositions x = 0.97 and 1.43), we found that a reorganization of bonds takes place at temperatures less than or equal to 500 degrees C, where the well-known cross linking reaction Si-Si + N-H --> Si-H + Si-N occurs without detectable release of hydrogen. In the same range of temperatures, an increase of the band gap was observed and attributed to Si-Si bond substitution for Si-H, but no changes in composition were detected. At higher temperatures (T greater than or equal to 600 degrees C), the optical gap decreases and both Si-H and N-H bonds are lost along with a release of hydrogen and nitrogen. For the films with an as-gown composition x = 1.55, we observe that the release of hydrogen only occurs at temperatures above 900 degrees C, but it is not accompanied by any loss of nitrogen. An increase of the optical gap until the release of hydrogen begins and a decrease thereafter is observed., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

With a high specific capacity and low electrochemical potentials, metal anode batteries that use lithium, sodium and zinc metal anodes, have gained great research interest in recent years, as a potential candidate for high-energy-density storage systems. However, the uncontainable dendrite growth during the repeated charging process, deteriorates the battery performance, reduces the battery life and more importantly, raises safety concerns. With their unique properties, two-dimensional (2D) materials, can be used to modify various components in metal batteries, eventually mitigating the dendrite growth, enhancing the cycling stability and rate capability, thus leading to safe and robust metal anodes. In this paper, we review the recent advances of 2D materials and summarize current research progress of using 2D materials in the applications of (i) anode design, (ii) separator engineering, and (iii) electrolyte modifications by guiding metal ion nucleation, increasing ion conductivity, homogenizing the electric field and ion flux, and enhancing the mechanical strength for safe metal anodes. The 2D material modifications provide the ultimate solution for obtaining dendrite-free metal anodes, realizes the high energy storage application, and indicates the importance of 2D materials development. Finally, in-depth understandings of subsequent metal growth are lacking due to research limitations, while more advanced characterizations are welcome for investigating the metal deposition mechanism. The more facile and simplified preparation of 2D materials possess great prospects in high energy density metal anode batteries, and thus fulfils the development of EVs.

Huge plastic consumption and depletion of fossil fuels are at the top of the world's envi-ronmental and energy challenges. The scientific community has tackled these issues through differ-ent approaches. Catalytic pyrolysis of plastic wastes to valuable products has been proved as a sustainable route which fits with the circular economy aspects. The design of catalytic materials is the central factor for performing the catalytic conversion of plastic wastes. This review aims to conduct a Bibliometric analysis of the pyrolysis of plastic wastes and non-precious-based catalysts by mapping research studies over the last fifty years. The analysis was developed via VOSviewer and RStudio tools. It showed the historical progress regarding plastic waste pyrolysis to produce valu-able products and chemicals worldwide. The research shows that the top five countries with the highest citations and publications in this field were Spain, China, England, the USA and India. The Journal of Analytical and Applied Pyrolysis had the most comprehensive coverage of plastic waste. The relationship between the catalyst and the mechanism of plastic waste can influence the production yield and selectivity. The research gap and underrepresented research topics were iden-tified, and previous research studies on developing non-precious-based catalysts that were most rel-evant to the current topic were reviewed and discussed. The challenges and perspectives on catalyst preparation and development for material complexity were critically discussed. Challenges of pre-vious studies and directions for future research were provided. This report might guide the reader to take a general look at plastic waste valorization by pyrolysis and easily understand the main chal-lenges. (c) 2023 The Author(s). Publis

Carbon materials and their diverse allotropes have played important roles in our daily lives and the advancement of material science. After 0D “Carbon 60” and 1D “carbon-nanotube,” 2D-graphene nanomaterials have attracted significant attention since 2004 because of their unique and exciting properties. Over the last decade, 3D-graphene nanomaterials have been developed to efficiently use 2D-graphene nanosheets in applications like energy storage, environmental remediation, and electrochemical catalysis. We describe 3D graphene materials, classify them, briefly discuss their history, and cover this review's basic synthesis chemical procedures. Special attention is given to their bibliometric analysis, advancement, synthesis, technical applications of energy storage devices, environmental applications, and supercapacitor-based applications. The CiteSpace (6.1. R3) software is used for the bibliometric analysis findings from 2012 to 2023 for keywords, countries, journals, co-occurrence, and co-author networks. Data were taken from 1142 papers, 71 review articles, and 1071 article proceedings over 12 years, from 2012 to 2023. The date of retrieval, November 10, 2022, was the latest.

We investigated the chemical vapor deposition synthesis of Mo2C/graphene heterostructures on a partially wetted liquid copper surface, studied the morphology of resulting phases using electron and optical microscopy, and determined the rate-limiting step for the growth of Mo2C on graphene. The morphology of the Mo2C crystals varied from the center to the edge of the copper substrate because of the change in the Mo diffusion pathways owing to the variation in the thickness of the Cu substrate. Thin, hexagonal-shaped crystals of Mo2C were found in the central region, where Cu is the thickest. In addition, the growth pressure substantially affects the nucleation and growth kinetics of both Mo2C and graphene. At high pressures (750 Torr), the graphene layer fully covered the Cu surface and Mo2C crystals formed with a regular shape, while at low pressures (5 Torr), the nucleation of both domains was suppressed, leading to the evolution of Mo2C crystals with irregular shapes. The activation energy for the growth of Mo2C on graphene was calculated to be 3.76 +/- 0.3 eV, and the diffusion of Mo to the Cu surface through uncovered Cu or graphene vacancies/defects was determined to be the rate-limiting step., Air Force Office of ScientificResearch, Grant/Award Number: FA9550-19-1-7048, Air Force Office of Scientific ResearchUnited States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-19-1-7048]

We investigated the chemical vapor deposition synthesis of Mo2C/graphene heterostructures on a partially wetted liquid copper surface, studied the morphology of resulting phases using electron and optical microscopy, and determined the rate-limiting step for the growth of Mo2C on graphene. The morphology of the Mo2C crystals varied from the center to the edge of the copper substrate because of the change in the Mo diffusion pathways owing to the variation in the thickness of the Cu substrate. Thin, hexagonal-shaped crystals of Mo2C were found in the central region, where Cu is the thickest. In addition, the growth pressure substantially affects the nucleation and growth kinetics of both Mo2C and graphene. At high pressures (750 Torr), the graphene layer fully covered the Cu surface and Mo2C crystals formed with a regular shape, while at low pressures (5 Torr), the nucleation of both domains was suppressed, leading to the evolution of Mo2C crystals with irregular shapes. The activation energy for the growth of Mo2C on graphene was calculated to be 3.76 +/- 0.3 eV, and the diffusion of Mo to the Cu surface through uncovered Cu or graphene vacancies/defects was determined to be the rate-limiting step., Air Force Office of ScientificResearch, Grant/Award Number: FA9550-19-1-7048, Air Force Office of Scientific ResearchUnited States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-19-1-7048]

[Abstract]: In this review, we will provide a comprehensive insight on the current research si-tuations and future challenges for the graphene-based implantable biosensors. We intro-duce the use of graphene derivatives for in vivo sensing implants, discussing their synt-hesis and key properties for this final application. Then the most promising recent exam-ples in the field were critically revised, with special attention to electrochemical and transistor-based biosensors. Although there are still many challenges to overcome, we can anticipate that the latest developments are paving the way for the next generation of this kind of implants. Finally, the emerging 2D materials are also presented, which are following the graphene pathway for the in vivo sensing field, with a broad future to explore.