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© 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

© 2001 American Institute of Physics. This work was supported by DGES ~Project No. PB96-0639!, the Russian R&D program ‘‘Nanostructures’’ (Grant No. 97-2016), and RFBR under Grant No. 98-02-17350., Synthetic opals-composed of 250 nm amorphous silica spheres closed packed in a face centered cubic structure-have been infilled with silicon, platinum, and with Si and different Pt contents. The luminescent properties of these composites have been investigated by cathodoluminescence (CL) microscopy and spectroscopy. CL emission is influenced by the material used to infill the pores of the opal matrix. CL spectra of all the samples investigated show two well-known bands, associated with the defect structure of the silica spheres, centered at about 1.9 and 2.7 eV, respectively. Emission in the 2.15-2.45 eV range, particularly intense in opal-based composites with a high Pt content, is tentatively associated with SiO2 defects involving silicon clusters. A CL band peaked at about 3.4 eV as well as a band in the 1.50-1.75 eV range, whose peak position seems to be affected by the Pt content of the samples, are associated with the presence of Si nanocrystals. The behavior of these emissions suggests that both are related to defect states at the interface between Si nanocrystals and SiO2 forming the opal spheres., DGES, Russian R&D program ‘‘Nanostructures’’, RFBR, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2007 American Institute of Physics. This work has been supported by MEC through project MAT2006-01259., V_2O_5 nanostructures have been grown on 4H-SiC and Si substrates by a thermal deposition method without a catalyst. High aspect ratio nanowires with rectangular cross sections were grown on 4H-SiC. High-resolution transmission electron microscopy observations and cathodoluminescence (CL) spectroscopy measurements reveal the high crystal quality of the grown nanowires. Deposition on Si substrates leads to the growth of V_2O_5 platelets or rod-shaped crystals ending in arrays of parallel sharp nanotips with apex radius in the 50 nm range. A CL emission band observed centered at about 1.70 eV in spectra from these nanostructures is tentatively attributed to defect centers involving oxygen vacancies., MEC, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 1996 American Institute of Physics One of the authors (P.S.D.) would like to thank CSIR (India) for the award of a senior research fellowship. U.P. gratefully acknowledges MEC (Spain) for the postdoctoral fellowship. This work was partially supported by the Universidad Autonoma de Madrid, Spain, through a visiting scientist fellowship and by DGICYT Project Nos. PB93-1256 and ESP95-014, Passivation of point and extended defects in GaSb has been observed as a result of hydrogenated amorphous silicon (a-Si:H) treatment by the glow discharge technique. Cathodoluminescence (CL) images recorded at various depths in the samples clearly show passivation of defects on the surface as well as in the bulk region. The passivation of various recombination centers in the bulk is attributed to the formation of hydrogen-impurity complexes by diffusion of hydrogen ions from the plasma a-Si:H acts as a protective cap layer and prevents surface degradation which is usually encountered by bare exposure to hydrogen plasma. An enhancement in luminescence intensity up to 20 times is seen due to the passivation of nonradiative recombination centers. The passivation efficiency is found to improve with an increase in a-Si:H deposition temperature. The relative passivation efficiency of donors and acceptors by hydrogen in undoped and Te-compensated p-GaSb has been evaluated by CL and by the temperature dependence of photoluminescence intensities. Most notably, effective passivation of minority dopants in tellurium compensated p-GaSb is evidenced for the first time., Universidad Autonoma de Madrid, Spain, DGICYT, Depto. de Física de Materiales, 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

© 2009 American Institute of Physics. This work was supported by MEC (Project No. MAT2006-01259)., Al doped ZnO arrays of nanoplates and of ordered nanoneedles have been grown by a thermal evaporation-deposition method. The nanoplates, which have mainly triangular shape. Interpenetrating triangles and crossing of the triangles with other planar arrangements form a structure consisting of arrays of microboxes. The influence of Al on the luminescence of the nanostructures has been studied by cathodoluminescence (CL) in the scanning electron microscope. Intense CL emission from the internal faces of the microboxes is related to the presence of deep level defects., MEC, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2005 American Institute of Physics. This work is supported by MCYT (Project No. MAT 2003-00455), Sintering SnO_2 under argon flow at temperatures in the range of 1350-1500 degreesC causes the formation of wires, rods, and tubes on the sample surface. At high temperatures of the mentioned range, microwires with lengths of hundreds of microns are formed. At lower temperatures the formation of micro- and nanorods as well as micro- and nanotubes takes place. The influence of ball milling of the starting powder on the formation of tubes is investigated. The local cathodoluminescence measurements show a different defect structure in the tubes than in the sample background., MCYT (Spain), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2004 American Institute of Physics. This work has been supported by MCYT (Project No. MAT2003-00455)., The effect of mechanical milling on the structure and luminescent properties of CdSe powder has been investigated by means of cathodoluminescence (CL) in the scanning electron microscope, transmission electron microscopy (TEM) and x-ray diffraction. The starting powders were ball milled for times between 5 and 20h. TEM of the milled samples reveals the presence of nanocrystals with a wide range of sizes including nanocrystals of 10 nm and smaller. The CL spectra of the untreated samples show the characteristic band edge emission centered at 1.8 eV. In the milled samples a band centered at about 2.5 eV is observed which appears to be associated to the presence of nanocrystals. The evolution of defect structure with milling time has been monitored by recording infrared cathodoluminescence spectra. A partial phase transformation from wurtzite to zinc blende structure also has been observed., MCYT, Depto. de Física de Materiales, 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