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3D sequential integration is a promising alternative to conventional scaling down approach: by stacking transistors level on top of each other, benefits on device density and performance are achieved. However, although the thermal processing of top transistors is currently restricted in order to avoid bottom CMOS degradation, it has been highlighted that Ni0.80Pt0.10 silicide source/drain (S&D) contact remains the most sensitive element to the thermal budget, especially on raised Si0.7Ge0.3:B S&D for pMOS transistors. In this context, a complete and systematic study on self-aligned silicide (SALICIDE) process has been proposed: alternative metallization as well as source and drain surface pre-treatments have been carried out. Indeed, a novel Ni-based silicide, the Ni0.9Co0.1 provides a better stability on unpatterned 300 mm wafers. This stability has been further improved when combined with epitaxial silicon capping layer (Si-Cap) and Si0.7Ge0.3:B S&D preamorphization implant (PAI) using Ge beam. For the first time, a successful Ni0.9Co0.1 SALICIDE implementation has been demonstrated on pMOS planar FDSOI transistor with both PAI and Si-Cap. Moreover, the presence of Si-Cap contributes to reduce silicide roughness and limits Ge partition that damage Si0.7Ge0.3:B S&D. [ABSTRACT FROM AUTHOR]

The presented study is the original analysis of hydrogen flow in channels with heterogeneous physical-chemical reactions. It provides the possibility to evaluate, calculate and predict unknown constants of heterogeneous reactions, using experimental data on dissociation at low pressures. It can be the base of conclusive data for computational modelling of CVD, using high velocity gas mixture flows. Till now there was no way to calculate the flow of hydrogen in tungsten channels in regimes of diamond deposition. The presented research allows formulate the problem of studies the heterogeneous reactions not only for diamond deposition. In the result of precise measurements of fragment fluxes behind heat-resistant capillaries from refractory metals or ceramics at low pressure and direct statistical simulation of gas mixture flows one can determine collisional constants for simple molecules. Such approach is more preferential than expensive and sophisticated molecular beam methods. So possibilities of CVD can be extended. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The lowest temperature for initiating the film deposition was evaluated by in situ monitoring using a highly sensitive langasite crystal microbalance (LCM) in order to produce a thin boron doped silicon film using trichlorosilane gas and boron trichloride gas at low temperatures. The thin films of silicon, boron and boron-doped silicon were individually formed from the trichlorosilane gas, boron trichloride gas and their gas mixture, respectively, on the LCM. The silicon film deposition occurred between 570 and 600 °C, while the boron film deposition occurred between 470 and 530 °C. The film deposition from both gases occurred at temperatures higher than 530 °C. Based on secondary ion mass spectrometry measurements, the boron-doped silicon film was determined to be formed on the silicon substrate at 570 °C. Thus, the LCM could be useful for developing a thin film formation process including that for doping. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We propose a method to apply amorphous alumina films on the inner surface of glass containers aiming to improve their hydrothermal barrier property. We have carried out alumina deposition on Si substrates as a function of deposition temperature to determine the physico-chemical properties of the thin film materials, and on glass containers to evaluate the influence of post-deposition hydrothermal ageing on the films properties. Film preparation has been achieved by metal-organic chemical vapor deposition (MOCVD), using tri-isopropoxide aluminum (ATI) dissolved in anhydrous cyclohexane as precursor, in a temperature range between 360 °C and 600 °C. A direct liquid injection technology is used to feed the reactor in a controlled and reproducible way. The amorphous alumina films have been characterized by several techniques such as XRD, EPMA, XPS, SEM, AFM and scratch-test method. Films are amorphous and hydroxylated at 360 and 420 °C and close to stoichiometric at 490 and 560 °C. Hydrothermal ageing simulated by a standard sterilization cycle modifies the adhesion and surface morphology of the alumina film on glass containers to a rough, porous and non-adhesive layer. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Amorphous, as shown by X-ray diffraction measurements, MoS2 films (a-MoS2) were deposited by heating a molybdenum wire at temperatures between 500 and 700 °C in H2S at 1 Torr. As shown by Scanning Electron Microscopy measurements, the morphology of samples depends significantly on the filament temperature; at low temperature samples are homogeneous and smooth, at intermediate temperatures they exhibit a granular microstructure and at high temperatures a columnar one. X-ray photoelectron spectroscopy measurements have shown S/Mo ratios in films varying between 2.5 and 1.5 dependent on filament temperature. Films also contain oxygen at atomic contents of 8 to 12%. As shown by XPS and Raman spectroscopy, at a filament temperature of 600 °C films are mainly composed of MoS2 also containing oxygen at an atomic ratio of 8%. Spectroscopic ellipsometry measurements made on a-MoS2 films have shown that their band gap is of the order of 1.4 eV, slightly higher than that for the bulk crystalline material. Photoluminescence spectroscopy measurements have shown that samples exhibit a doublet of peaks at 2.8 and 3 eV blue shifted relatively to MoS2 samples composed of one or two mono-layers. The above indicate that the electronic structure of crystalline atomic-layer thick MoS2 is preserved in a-MoS2 films. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

High quality injection molding requires a precise control of cooling rates. Thermal barrier coating (TBC) of zirconia with a thickness of 20-40 µm on polished stainless steel molds could provide the necessary insulating effect. This paper presents results of zirconia deposition on stainless steel substrates using chemical vapor deposition (CVD) aiming to provide the process parameters for the deposition of uniform zirconia films with such a thickness. The deposition was performed with zirconium (IV) acetylacetonate (Zr(C5H7O2)4) as precursor and synthetic air as co-reactant, which allows deposition at temperatures below 600 °C. The experiments were carried out in a hot-wall reactor at pressures between 7.5 mbar and 500 mbar and in a temperature range from 450 °C to 600 °C. Important growth parameters were characterized and growth rates between 1 and 2.5 µm/h were achieved. Thick and well adhering zirconia layers of 38 µm could be produced on steel within 40 h. The transient heat transfer rate upon contact with a hot surface was also evaluated experimentally with the thickest coatings. These exhibit a good TBC performance. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We report on the growth kinetics and material properties of aluminium nitride (AlN) films deposited on Si(111), with plasma enhanced atomic layer deposition (PEALD). Tri-methyl aluminium (TMA) and NH3-plasma were used as the precursors. The ALD window was identified in terms of the process parameters, and it showed that a 0.1 s of TMA pulse, 8 s of NH3-plasma pulse, and 350 °C were the optimal conditions for ALD to occur. In-situ spectroscopic ellipsometry (SE), using a Cauchy optical model, was used to monitor the film growth in real time. The composition of the as-grown AlN films were determined by X-ray photoelectron spectroscopy (XPS), which revealed Al/N compositions of approximately 46% and 53%, also with low impurity (O, C) levels. The film crystallinity, measured with grazing incidence X-ray diffraction (GIXRD), showed polycrystalline hexagonal (wurtzitic) crystalline planes. Finally, several techniques were employed to influence the film crystallinity. These included: ALD at different plasma powers and temperatures, in-situ treatment of the Si(111) wafer with different plasma parameters (composition, power, duration) prior to deposition, and ALD on Si(100) and SiO2 substrates. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Research on high-performance CVD coatings follows the target to increased hardness and oxidation resistance. Such coatings and coating systems are required for machining tools to optimize the manufacturing parameters for new materials and new processes. The use of chromium-containing coatings is requested because of its feature to increase the corrosion resistance. The production of various chromium-containing coatings is already shown by PVD, but for industrial scale CVD processes there are problems with the chromium precursors. Especially the chromium chlorides have a low vapour pressure and therefore high temperatures are needed for evaporation. To overcome the disadvantages of CrCl3 the relatively good evaporation of halide complexes was reported, showing potential for new CVD processes. Numerous metal compounds form gaseous complexes with Aluminium chloride but also Cr. Based on this characteristic the transport reaction of CrCl2/Al2Cl6 as chromium tetrachloraluminate is investigated. The focus of this work lies in the preparation of the chromium precursors as well as in the optimization of the transport reaction which required various changes in the conventional experimental CVD-setup. To measure the amount of transported chromium the gas phase was condensed and their Cr-content was analyzed. For the CVD deposition of Cr containing coatings, this precursor gas flow can be used directly. Further the interaction between aluminum chloride and the chromium precursor, different process parameters, as well as existing difficulties regarding the transport reaction are discussed. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The development of a new process to obtain amorphous alumina thin films is presented. We show for the first time the direct liquid injection chemical vapor deposition (DLI CVD) of alumina thin films using dimethylaluminum isopropoxide (DMAI) precursor in two oxidizing atmospheres. At high process temperature (500-700 °C), the film growth takes place in the presence of O2 whereas at low temperature (150-300 °C) H2O vapor is used. The materials characteristics, such as the surface morphology and roughness (SEM and AFM), crystal structure (XRD), composition (EPMA) and chemistry (XPS) are discussed in detail. Very smooth films, with typical roughness values lower than 2.0 nm are obtained. The thin films are all composed of an amorphous material with varying composition. Supported by both EPMA and XPS results, film composition evolves from a partial oxyhydroxide to a stoichiometric oxide at low deposition temperature (150-300 °C) in the presence of H2O. At higher growth temperature (500-700 °C) in the presence of O2, the composition changes from that of a stoichiometric oxide to a mixture of an oxide with aluminum carbide. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Experiments on chemical vapor deposition of W(CO)6-derived films on silicon substrates were carried out at total pressure of 5-10 Torr within the temperature range of 250-350 °C; in Ar or H2 flow. Metallic, carbide and oxide phases composed the obtained films. Deposition in presence of hydrogen results in the increase of the metal content in the film. Sublimed palladium hexafluoracetylacetonate Pd(hfa)2 was used for Pd catalytic promotion of the deposition process. Codeposition with Pd(hfa)2 in hydrogen increases W-metal fraction and oxygen content while the Pd content is up to 10 at.%. Influence of vacuum ultraviolet (VUV) radiation from Xe excimer lamp ( λ ∼172 nm) on the quality of the obtained films was investigated. It was found that VUV irradiation can reduce the oxygen-content in the film while W-metal fraction slightly increases. In all films, oxygen was in the form of WO3 and carbon was mainly incorporated as a graphite metastable phase. The influence of other chemical additives is discussed. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The article covers the computational framework providing an insight on vapour phase coagulation of nanoparticles synthesized by atmospheric pressure PECVD in an RF capacitive discharge. The proposed model is based on the solution of motion equations for neutral and charged nanoparticles in the plasma downstream area featuring a nonuniform distribution of electric potential. Within the model particles collisions are accounted by an O'Rourke derived stochastic method, reduction of computational time is attained by division of the nanoparticle stack into parcels. We argue that nanoparticles are mainly synthesized in the plasma downstream area. Size distribution of the particles is governed by their uneven motion in the nonuniform electric field. We demonstrate that particles of tens of nanometer in diameter result from coagulation of neutral nanoparticles, whereas the larger nanoparticles result from coagulation of charged particles. The model shows that charged particles trapped in the potential well in the vicinity of the discharge electrode grow up to micron size. The proposed model is validated by the experimental results of silicon dioxide nanoparticles synthesis; it may be extended to a vast range of materials provided certain modifications of the particles motion equations are done. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The relative rates of adsorption and irreversible reaction are modeled for a prototypical atomic layer deposition (ALD) system. Surface species balance modeling equations are processed through a reaction factorization procedure to eliminate redundant dynamic modes. The resulting singular perturbation problem then is used to develop a criterion that distinguishes between mass-transfer and kinetically-limited deposition regimes for this dynamic process. Detailed simulations of a TMA/water alumina ALD process are used to evaluate our analysis approach and to demonstrate the dominance of mass-transfer limitations for this system during both precursor exposure periods. Our analysis shows the increasing likelihood of encountering mass-transfer limitations at reduced temperatures, a finding opposite of what might be expected. We find that the ALD dynamics evolve on a manifold defined by the balancing of adsorption and irreversible reaction rates, further reducing the dynamic dimension of the deposition dynamics. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We investigated the electronic structure of BaFeO3 by using HAXPES and XAS measurements and first principle studies. The experimental and theoretical results indicated that BaFeO3 is a negative charge transfer compound. We concluded that the on-site Coulomb energy and the strong hybridization between Fe-3 d and O-2 p orbitals play a very important role of emergence of negative charge transfer. And we found the new structure in the Fe-2 p XPS spectrum and concluded this structure is originated from non-local screening. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Optical properties of the quaternary Cu2ZnSnS4 semiconductor have been studied by optical absorption, photoluminescence, photoreflectance, and thermoreflectance measurements. Optical absorption measurements suggest that Cu2ZnSnS4 is a direct-gap semiconductor having the band gap of ∼1.46 eV at 11 K. The photoreflectance and thermoreflectance spectra reveal distinct structures at energies of the critical points in the Brillouin zone. By performing the band-structure calculation, these critical points are successfully assigned to specific points in the Brillouin zone. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Visible-light transparent solar cells were fabricated using p -type NiO and n -type ZnO by conventional RF reactive sputtering with NiZnO alloy as an intrinsic interlayer. The energy band diagrams of NiO/NiZnO/ZnO heterojunctions were revealed by photoelectron yield spectroscopy, and the band gap energies were estimated to be 1.2 eV for NiO/Ni0.4Zn0.6O and 0.6 eV for Ni0.4Zn0.6O/ZnO heterojunctions. By using In2O3:Sn (ITO) as a transparent electrode in NiO-based visible-light transparent solar cells, a small but noticeable photovoltaic effect was obtained. The short-circuit current density (Jsc) increased from 4 μA/cm2 to 12 μA/cm2 due to the insertion of Ni0.4Zn0.6O interlayer. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The investigation of the radiation degradation characteristics of InGaP space solar cells is important. In order to understand the mechanism of the degradation by radiation the samples of the InGaP solar cell were irradiated in vacuum and at ambient temperature with electron beams from a Cockcroft-Walton type accelerator at Osaka Prefecture University. The threshold energies for recoil were obtained by theoretical calculation. The energies and the fluences of the electron beams were from 60 to 400 keV and from 3×1014 to 3×1016 cm-2, respectively. The light-current-voltage measurements were performed. The degradation of Isc caused by the defects related to the phosphorus atoms was observed and the degradation was suppressed by irradiation at an energy higher than the threshold energy for recoiling Indium atoms. At an energy of 60 keV, where the recoil does not occur, the Voc was degraded. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Transparent electrode is a key component in the multi-junction solar cells, working as window and intermediate electrodes. It requires high transparency for wide range and suitable electrical junctions. Graphene, a single atomic layer of sp2 graphitic carbon, is one of alternative materials. We demonstrated a-Si thin film solar cells with high-quality graphene grown by chemical vapor deposition. The graphene-cell showed higher open-circuit voltage compared with conventional transparent conductive oxide. It might be a contribution of lower Schottky barrier at graphene/p-layer interface. Our experimental results demonstrated a high potential of graphene transparent electrode not only for a-Si solar cells but also for multi-junction solar cells. [ABSTRACT FROM AUTHOR]

Preparation method and photoluminescence properties of Mg2(Ti0.99- x - y, Ge x, Si y)O4:Mn phosphor for white LED was studied. The obtained powders showed deep red emission around 670 nm under blue light excitation. The PL intensity depended on the ratio of IV atoms, and PL spectra depended on the IV atom consisted in the phosphors. It was found that the ternary or multinary compounds showed higher luminescence. It indicates that the properties of Mg2(Ti0.99- x, Ge x)O4:Mn might much improve by preparation of completed alloy. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

By ab initio calculation using the ABCAP code, energy shifts of core levels and optical properties of B-incorporated AlN (AlBN) were examined through comparison with experimental spectra measured from the thin film. Good agreements of complex refractive indices, n and k, with experiment were obtained for pure AlN and pure BN. However, when B content is increased in AlBN, substantial disagreement is found between experiment and calculation that assumed either wurtzite or graphite-like structure for clarity. These results suggest that AlBN with ca. 30% is neither complete solid solution nor grain-level mixture of graphite like BN and AlN. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Si-codoped CuAlS2:Mn thin films have been prepared by EB evaporation using the phosphor powder as evaporation source pellets. The selective substitution of Mn centers for both Cu and Al has been first achieved for thin film samples. A currently obtained maximum quantum efficiency is about 9% for an orange emission due to Mn centers substituted for Cu, and 3% for a red emission due to Mn centers substituted for Al. It has been found that the conductivity predominantly depends on the Al/Cu compositional ratio of the thin films. The origin of carriers is considered to be the Cu-Al mutual substitution. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu(In,Ga)Se2 (CIGS) crystals were synthesized by a mechanochemical (MC) process using a crank ball mill. The molar ratios of starting materials were Cu:In:Ga:Se=1:1-x:x:2 (0≤x≤1) and Cu:In:Ga:Se=1:0.7:0.3:y (2≤y≤3). The reaction time reduced with decreasing Se and Ga molar ratios. The collection rate decreased with longer reaction times. From XRD patterns, we confirmed that the CuInSe2 and/or CuGaSe2crystals were successfully grown when the powders reacted. Although the crystals grown with a selenium molar ration of 2 were Se-poor, those grown at a molar ratio of 3 were Se-rich. When Se increasing molar ratio, Cu, In, and Ga were away from the stoichiometric. With a molar ratio of Cu:In:Ga:Se=1:0.7:0.3:2.5∼2.7, their composition became stoichiometric. Crystal morphology was varied. CIGS crystals were thus successfully synthesized using a crank ball mill. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A table of contents for the No. 6, 2015 issue is presented.

The 19th International Conference on Ternary and Multinary Compounds (ICTMC-19) was held on 1-5 September 2014 at Toki Messe, Niigata, Japan. This conference, part of the series of conferences that began in 1973 in Bath, was held traditionally as an interdisciplinary forum for the exchange of information and experience in the exciting field of materials science of ternary and multinary compounds. It was then held in Strasbourg (1975), Edinburgh (1977), Tokyo (1980), Cagliari (1982), Caracas (1984), Snowmass (1986), Kishinev (1990), Yokohama (1993), Stuttgart (1995), Salford (1997), Hsin-chu (2000), Paris (2002), Denver (2004), Kyoto (2006), Berlin (2008), Baku (2010), and Salzburg (2012). The conference brought together researchers for the discussion of the latest developments and achievements in the field of these complex materials. The scientific program included two plenary talks, 20 invited talks, 13 symposium talks, 50 oral presentations, and 112 poster presentations from the following 15 countries: Japan, Taiwan, Azerbaijan, Germany, Korea, Thailand, USA, Philippines, France, Belgium, China, Mexico, Moldova, Turkey, and UK. Of the papers, 95 are included in the present proceedings volumes of physica status solidi. The Conference covered physics, chemistry, materials science, device engineering, and the growth and theory of various ternary and multinary compounds: chalcopyrite-type (I-III-VI2, II-IV-V2), kesterite-type (I2-II-IV-VI4), sphalerite-type and wurtzite-type (III-V, II-VI, etc.), perovskite-type, skutterudite-type, complex-oxides, complex-nitrides, and so on. Three symposiums in the conference were focused on new photovoltaic materials superior to CIGS, advanced characterization of solar cells, and mulitinary materials in the next generation. The Program Committee picked up three young members as the winners of the 'Best Young Scientists Award' for their excellent presentations. The winners are Galina Gurieva, Ayaka Kanai, and Tsuyoshi Maeda. The Guest Editors wish to express their gratitude to the members of the International Advisor Committee, the Program Committee, the sponsors, the Japanese Professional Group of Multinary Compounds and Solar Cells in the Japanese Society of Applied Physics, and thank all those who have contributed to this conference for their support and advice. We are very grateful to the referees for their contributions during the editorial process. The next anniversary conference of ICTMC-20 will be held in Germany, chaired by Prof. Roland Scheer. We convey our best wishes to the organizers for a successful meeting. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Oleylamine-capped tin disulfide nanoparticles were prepared by the hot-injection method using tin (II) chloride (SnCl2.5H2O) and thioacetamide as tin (II) and sulfur precursors, respectively. The as-prepared nanoparticles were rinsed with ethanol or toluene, and their structural and morphological were assessed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The obtained nanoparticles were single-phase SnS2 with hexagonal structure. These nanoparticles self-assembled to produce spherical 40-50 nm nanostructures after ethanol evaporation, whilst rhombohedral-shaped nanostructures or round-edge nanoribbons were produced after the toluene evaporation. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cadmium sulfide thin films on soda lime substrates were obtained by rf-magnetron sputtering in argon-oxygen atmosphere. As-prepared and vacuum annealed films were then studied by spectroscopic ellipsometry at room temperature over photon energy range from 0.5 to 6 eV. The obtained ellipsometric data were treated using optical dispersion models based on Gaussian type oscillators. Dielectric function of oxygen-free films, as well as those obtained under 3% of O/Ar partial pressure was reliably restored. At the same time, dielectric function obtained for 5% CdS:O can be regarded only as an average over several materials since our XPS examination disclosed presence of several compounds in thin films deposited at O/Ar ratios higher than 3%. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) material has many advantages for high-efficiency thin-film solar cell absorber layer. A detailed study of the surface of the CZTS and the hetero-interface of the CZTS/buffer layer is important to improve the conversion efficiency of CZTS thin film solar cells. We investigated the surface condition of the CZTS films by carrying out the surface treatment using bromine solution. The activation energy of the etching using bromine solution was estimated from the slope of the line fitting the graph of the temperature dependence of the etching rate. The activation energy is about 0.35 eV. This value suggests that etching mechanism of CZTS using bromine solution is diffusion-limited process. There were no significant changes in the structural characteristics after surface treatment by X-ray diffraction and Raman spectroscopy. From the results of X-ray photoelectron spectroscopy measurements, a relative surface composition was shifted to Cu- and Zn-rich phase after surface treatment. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this work, we investigated the effect of surface treatment of the Cu2ZnSnS4 (CZTS) thin films using ammonia solution. CZTS thin films were prepared by RF sputtering using single CZTS target with sulfurization process. In order to study the effect of surface treatment using ammonia solution, solution temperature was varied. Structural properties of the samples are almost same with and without ammonia surface treatment measured by XRD and Raman spectroscopy. From the measurement of the chemical composition, the Zn is dissolved by ammonia solution. In addition, the removal rate of oxygen and sodium is different between deionised water and ammonia solution. Ammonia could have prevented their removal from the surface to solution. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The substitution energies and migration energies of the alkali-metals of Li, Na, and K atoms in Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) were investigated by first-principles calculations. The migration energies of Li, Na, and K atoms in CZTS and CZTSe are obtained by a combination of linear and quadratic synchronous transit (LST/QST) methods and a nudged elastic band (NEB) method. For CZTS and CZTSe, the substitution energies of NaCu and NaZn are much smaller than that of NaSn. The substitution energy of NaZn is comparable to that of NaCu, indicating that NaCu and NaZn are easily formed in CZTS and CZTSe. The substitution energies of the LiCu and LiZn atoms are smaller than those of NaCu and NaZn, while substitution energies of KCu and KZn atoms are much larger than those of NaCu and NaZn. Therefore, it is difficult to form KCu and KZnin CZTS and CZTSe. The theoretical migration energies of Na atom at Cu site to the nearest Cu vacancy (NaCu→VCu) and Na atom at Zn site to the nearest Cu vacancy (NaZn→VCu) are much smaller than those of (NaSn→VCu). The migration energies of (NaCu→VCu) and (NaZn→VCu) in CZTS and CZTSe are comparable to that of Na atom at Cu site to Cu vacancy (NaCu→VCu) in CIS. The mechanism for the alkali-metal effect of Li, Na, and K in the Cu2ZnSn(S,Se)4 films during the post-deposition treatment of LiF, NaF, and KF is discussed on the basis of the calculated substitution and migration energies. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Doping properties in ZnSnAs2 compound semiconductors were studied by the first-principles spin-polarized calculation. We have shown that the Ga doping into Zn site produces an ideal n-type system with small effective mass, not sensitive to the doping concentration, which feature merits the optical isolator application. On the other hand, the Mn doping into Sn site induces a large spin moment around S=1, which merits the spintronics application. When the Mn concentration is increased, however, Mn atoms prefer to locate nearby and the spin moment decreases by the anti-ferromagnetic interaction between Mn atoms. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We have grown Ga doped ZnSnAs2 thin films on InP substrates using all-solid source MBE technique. Using the optimum substrate temperature of 340 ºC and Zn:Sn:As4 beam equivalent pressure ratio (BEPR) of 24:1:52, samples were prepared with different Ga concentration achieved by changing the Ga flux. Compositional analysis was performed using electron microprobe microanalysis (EMPA). We found that Ga concentration on the cation sites is 20.9% and 8.7%. XRD patterns of Ga doped samples showed only assignable to ZnSnAs2:Ga and InP substrate. The lattice constant decreases linearly from 0.5862 to 0.5829 nm with decreasing Ga concentration. The observed concentration dependence indicates that the lattice constant of the thin films can be controlled by Ga doping concentration. Hall coefficient and resistivity of Ga 8.7% doped sample can be well explained by the impurity band model. We were able to resolve the experimentally obtained carrier concentration pexp and mobility μexp into valence band carrier concentration pv with mobility μv and acceptor band carrier concentration pa with mobility μa. The computed apparent values papp and μapp are in good agreement with pexp and μexp, respectively. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) is one of the promising materials for high efficiency thin film solar cells. Here we report on the chemical and structural characterization of the CZTS thin films before and after the surface treatment using deionized water. X-ray diffraction and Raman scattering spectroscopy results showed that the deionized water treatment did not affect the bulk characterization. Copper chemical composition ratio increases and sulphur composition ratio decreases with increasing deionized water treatment temperature on the film surface. In the case of the sample treated at 353 K, the surface composition changes to Cu-rich composition. However, the chemical composition ratio of the bulk still remained before deionized water (DIW) surface treatment. The change in the CZTS surface composition according to the DIW surface treatment temperature, we think these results may help to be studied in CZTS surface in more detail. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The morphological and structural transition of Cu2SnS3 (CTS) thin films during sulfurization was investigated. The surface morphology and re-evaporation of CTS films strongly depend on the sulfurization temperature. Low temperature sulfurization enables the films to be sulfurized and form CTS without re-evaporation. Subsequently, the high-temperature annealing improves the grain size of the CTS film. In addition, the energy band diagrams of the CTS-related solar cell structures that use various n- type oxide semiconductors, such as CdS, ZnO:In2O3(IZO), ZnO, SnO2, and ZnO:SnO2(ZTO) were examined by photoelectron yield spectroscopy. The band diagrams of IZO/CTS, ZnO/CTS, SnO2/CTS, and ZTO/CTS have a TYPE-I heterostructure known as a 'spike' conduction band offset structure, essential for high-efficiency solar cells. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2ZnSnSe4 ingot was synthesized and then used it and Na2Se powder as evaporation materials to prepare a precursor for selenization process in order to fabricate Cu2ZnSnSe4 thin films for solar cell applications. From EPMA analysis, the Sn content in the thin films was approximately constant with increasing Sn mole ratio and the Se content was under 50 at.% in the first experiment. The Se content in the thin films increased to around 50 at.% by the addition of Se layer in second experiment. XRD study showed that the thin films had a kesterite phase in Cu2ZnSnSe4. The Se layer addition enhanced to grow thin films having a close-packed structure and columnar grains. Cu2ZnSnSe4 thin film solar cells demonstrated Voc= 282 mV, Isc= 3.00 mA/cm2. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

(Cu1-xAgx)2ZnSnS4 (CAZTS) and (Cu1-xAgx)2ZnSnSe4 (CAZTSe) solid solutions with 0 ≤ x ≤ 1.0 were synthesized. Their crystal structures were analyzed by Rietveld refinement of X-ray diffraction data. The refined lattice constants a of the kesterite-type CAZTS and CAZTSe increase with Ag content (x) increasing, while their lattice constants c slightly decrease. Therefore, by increasing x, the c / a ratio decreases from 2 for Cu-based compounds to a value lower than 1.9 for Ag-based compounds. The band-gap energies ( Eg) of CAZTS and CAZTSe solid solutions were determined by their diffuse reflectance spectra. The reflectance edges of the CAZTS and CAZTSe shifted to the longer wavelength side with Ag content increasing at 0.0 ≤ x ≤ 0.2, while they shifted to the shorter wavelength side at 0.2 ≤ x ≤ 1.0. By increasing x, the Eg of CAZTS decreases from 1.49 eV (x=0.0) to 1.47 (x=0.2) and then increases to 2.01 eV (x=1.0); and the Eg of CAZTSe decreases from 0.98 eV (x=0.0) to 0.95 (x=0.2) and then increases to 1.34 eV (x=1.0). There is small bowing in the band gaps of the CAZTS and CAZTSe systems. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We have studied the structure and optical properties of CdS:O films deposited on SLG (soda lime glass) substrates by cathode sputtering in the atmosphere of oxygen/argon gases. According to X-ray diffraction (XRD) and confocal Raman scattering data, the films annealed in vacuum at temperatures above 300 °C exhibited crystalline structure of CdS. On the other hand, XRD, confocal Raman scattering, AFM (atomic force microscopy) and TEM (transmission electron microscopy) data indicated amorphous structure nano-crystallization in CdS:O films annealed in vacuum at 400 °C. For the films, the emissions located at 3.35 eV were evident from photoluminescence measurements. The origin of this energy gap is discussed by taking into account redistribution of electronic density of states in the amorphous phase and quantum-size effect. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) spectra in the band-edge region of bulk single-crystals of layered ternary chalcogenide TlGaSe2 were examined at low temperature using confocal microscopy. Obvious PL emission near the band-edge region appeared only when the excitation light travelled in the direction normal to the c axis of the crystal structure of TlGaSe2. The observed PL spectra were resolved into two Gaussian peaks, A and B, located at 2.01 and 2.10 eV, respectively. By analyzing the excitation intensity dependence of the PL intensity, we assigned peak B to proper free excitons, whereas peak A seems to represent free excitons derived from the distorted crystal structure of TlGaSe2. This is the first observation of free excitons in TlGaSe2 by PL measurement. We also examined the temperature dependence of the PL intensity. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this work, bulk Cu2ZnSnS4 (CZTS) poly-crystals which were used as a target of the pulse laser deposition (PLD) method were grown using the solid-phase method. The CZTS poly-crystals were then investigated using X-ray diffraction (XRD), Raman spectroscopy, and compositional analyses. It was observed that impure crystal phases were reduced with increasing heat growth duration, and they almost completely disappeared in the crystals grown for 96 h at 980 °C. The lattice constants of the a and c axes were estimated from the XRD data and found to be 5.4307 Å and 10.8680 Å, respectively, which are in good agreement with the standard values of 5.4340 Å and 10.8560 Å, as according to JCPDS Card 01-075-4122. Our results indicate that the CZTS poly-crystals have either a kesterite or a stannite structure. Raman spectra confirmed the existence of CZTS without any secondary phases in the form of binary or ternary sulfides. CZTS poly-crystals were found to be nearly stoichiometric, and they possessed a uniform composition. CZTS thin films were deposited using the PLD method, and were evaluated using X-ray diffraction (XRD), composition analysis, and field emission scanning electron microscopy (FE-SEM). Very few additional impurity phases were detected in CZTS thin films deposited at a pulse energy density of 5 mJ/mm2. Finally, the composition of the CZTS thin films was not consistent with that of the CZTS poly-crystals as a target of PLD method. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A CuxZnyS/ZnS transparent pn heterostructure was successfully fabricated by the photochemical deposition (PCD) from aqueous solutions. In PCD, the substrate was immersed in the solution to a depth of about 2-3 mm from solution surface, and irradiated with the light of an ultra-high-pressure mercury arc-lamp through a lens. The growth solution of CuxZnyS contained 5 mM CuSO4, 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. The growth solution of ZnS contained 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. p-type conduction of CuxZnyS and n-type conduction of ZnS were confirmed by the photoelectrochemical measurement. Both the films had high optical transmission (>70%) in the visible range. The CuxZnyS/annealed-ZnS heterostructure showed rectification properties and photoresponse to AM1.5 irradiation. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

ZnSnP2 is a promising candidate for solar absorber materials from the viewpoint of high absorption and earth-abundant constitution elements. In this paper, we fabricated ZnSnP2 crystals by flux method based on the phase diagram of Sn-ZnP2 pseudo-binary system and investigated their properties for an application to photovoltaics. The crystal growth experiments with the cooling rate of 0.7 and 12 °C/h were carried out and we successfully obtained ZnSnP2 crystals with the diameter of 8mm and the thickness of a few mm by a slow cooling rate. The structure of grown crystals studied by X-ray diffraction was indicated to be chalcopyrite-type ZnSnP2. In addition, the decrease of the degree of order was observed with the increase of cooling rate. The lattice constants of a and c axes are 5.649 and 11.295 Å, respectively. The composition of grown crystals is a near stoichiometric ratio of ZnSnP2 by EDX analysis. The bandgaps of ZnSnP2 crystals obtained by cooling rate of 0.7 and 12 °C/h were estimated to be 1.61 and 1.48 eV, respectively, which is caused by the difference of the degree of order. The hall-resistivity measurement showed that ZnSnP2 crystals with a slow cooling rate has a p-type conduction. The resistivity, the hole concentration and the mobility are 10∼70 Ωcm, 6·1016∼2·1017 cm-3, and 1∼3 cm2V-1s-1. The obtained properties are suitable for an absorber of photovoltaics. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Zinc aluminate (ZnAl2O4) nanopowders were synthesized by co-precipitation method using zinc chloride and aluminum chloride as starting precursors. The calcination temperature which was a crucial preparation factor was varied and its influence on relevant physical properties of the product was investigated. Structural properties of synthesized nanoparticles were investigated by X-ray diffraction, X-ray absorption spectroscopy, scanning electron microscope, and Raman spectroscopy. The results suggest that that ZnAl2O4 in spinel structure with high crystallinity can be obtained after calcination beyond specific temperature affirmed by XRD results. Raman result indicates the correlated chemical bonding relating to the formation of ZnAl2O4 structure. Meanwhile, the Zn K-edge X-ray absorption near-edge structure (XANES) spectra of these samples with different calcination temperature obtained from the synchrotron X-ray absorption spectroscopy measurement show the existence of accurate oxidation state for zinc ion (Zn2+) in the spinel crystal structure. Moreover, it is revealed that the calcination temperature has significant effect on the local environment of the zinc absorbing atoms through the interesting change of white line appearance. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2SnS3 is a promising compound for use as an absorber layer in thin film solar cells because it is made up of low-cost and abundant elements, and has a high optical absorption coefficient. However, the band gap energy of monoclinic Cu2SnS3 is less than the value required for absorber layers in single-junction solar cells. On the other hand, the band gap energy of Cu2SiS3 was reported to be approximately 2.5 eV, which is sufficiently large for this purpose. Therefore, in the present study, an attempt was made to synthesize Cu2Si x Sn1- xS3, which is a solid solution between Cu2SnS3 and Cu2SiS3. In X-ray diffraction patterns from the synthesized compounds, the diffraction peaks were found to shift to higher 2 θ values with increasing x, indicating a decrease in the lattice constants. In addition, the estimated band gap energy increased from 0.85 to 2.56 eV with increasing x. Cu2Si x Sn1- xS3 is therefore a potential candidate for use as the absorber layer in thin film solar cells because its band gap energy can be adjusted simply by varying its composition. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The percolation threshold (PT) temperatures Tc1,c2 of two non-equivalent Ag+1,2 ions in Ag2S and Ag2Se lattices were determined from the temperature dependence of low-frequency (25-106Hz) impedance spectroscopy measurements. At PT temperatures Tc1≈200 K and Tc2≈ 334 K, an abrupt increase of the dielectric function ε1(ω) of Ag2Se crystal from a very large negative value, ε1 ≈-109, to a very large positive value ε1≈ 106 was observed, which is assumed to result from the dipole relaxation. The strong peaks of the dielectric losses ε2(ω), tgδ(ω) and impedance Z in Ag2Se were also determined at Tc1,c2. Two significant peaks in ε1(ω), ε2(ω)and tgδ(ω) were observed at Tc1≈ 312-320 K. and Tc2≈ 380-430 K in the temperature dependences of these parameters. The measured parameters decreased significantly with increasing frequency, confirming the long relaxation times. The drastic decrease at T > 430 K of ε1from a very large positive value 109to a very large negative one -108 is in accordance with infrared (IR) ellipsometry measurements; this indicates that electrons of Ag+- ions are ionized because of the high dielectric function screening of lattice sites before the known β→α structural phase transition from monoclinic to a body-centered cubic (bcc) structure. In addition, the activation energies of Ag+1,2 ions were estimated for Ag2S and Ag2Se crystals. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Temperature dependent infrared (IR) and optical spectroscopic ellipsometry methods are used to investigate peculiarities of the transitions from the ionic conductivity to the superionic conductivity states in Ag2S and Ag2Se compounds. The structural phase transitions (SPTs), known as β→α transition in these semiconductors, are investigated also with spectroscopic ellipsometry methods. The electronic band structure of Ag2S at the SPT changes sharply from the monoclinic to the bcc phase, which occurs at T = 453 K in the super ionic conductivity state, where all the interband transitions in optic region, corresponding to the monoclinic structure of β-phase, disappear. The α-phase of Ag2S is characterised with new lines in the dielectric functions ε1 and ε2, which arise at 5-6.5 eV. The interband transitions do not change in the SPT from the orthorhombic to the bcc in Ag2Se, which occurs at T > 406 K. In IR ellipsometry for the degenerated Ag2Se, the free carriers' plasma energy is displaced abruptly from ħω=0.075 eV at T=300 K to ħω=0.125 eV at T=338 K. The same effect is seen in the IR ellipsometry for Ag2S, where negative ε1 appears at T=434-440 K. These facts indicate a drastic increase of the free carriers concentrations in both of the semiconductors at temperatures before the β→α SPT. In Ag2S the second abrupt shift of the free carriers plasma energy from 0.035eV to 0.1 eV occurs at T=453 K, corresponding to β→ α SPT. The second shift is due to the electronic band structure change of Ag2S. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The 2-µm-thick Cu(In,Ga)Se2 (CIGS) absorber is divided into two areas, low defect density layer (front side) and high defect density layer (back side). In this paper, the optimized thickness of the low defect density layer and the high defect density layer is estimated for high cell performance. The optimization is performed by using device simulator. As a result, the high defect density layer (back side) has no influence on cell performance in the case of CIGS with high optical-absorption coefficient owing to almost no photocarriers, which are generated in the high defect density layer. In addition, the necessary thickness for absorbing all light to obtain high conversion efficiency is considered. CIGS with graded band profile can be thinner than that with flat band profile for high cell performance owing to the aid of back surface field. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this article, a high-performance AlGaN/AlN/GaN high electron mobility transistor (HEMT) with broad gate-to-source operation voltages is fabricated and demonstrated. The experimental results exhibit a maximum extrinsic transconductance of 94.2 mS/mm at VGS = -2.58 V and a threshold voltage of -3.68 V at drain output current of 1 mA/mm.The insertion of an AlN interfacial layer can enhance the carrier confinement ability in channel and extend the gate operation voltage to +5 V. Furthermore, the effect of gate recess on device performance is investigated by two-dimensional simulation. The simulated results show that the AlGaN/AlN/GaN HEMT with gate recess structure has higher equivalent Schottky barrier height, larger electron concentration in channel, larger drain output current and transconductance as compared with the device without gate recess structure. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this work, we present an investigation of the optical properties and band structure calculations for the photonic crystal structures (PCs) based on one-dimensional (1D) photonic crystal. Here we use 1D A5B6C7(A:Sb; B:S,Se; C:I) based layers in air background. We have theoretically calculated photonic band structure and optical properties of A5B6C7(A:Sb; B:S,Se; C:I) based PCs. In our simulation, we employed the finite-difference time domain (FDTD) technique and the plane wave expansion method (PWE) which implies the solution of Maxwell equations with centered finite-difference expressions for the space and time derivatives. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

This work focuses on the creation of logic circuits by employing the collective dynamics of assembles of reciprocal memristors. A novel circuit design methodology is described where the computing systems comprise passive memristors interfaced with active CMOS circuitry, working under already known circuit design principles from the CMOS technology. The accuracy and completeness of this straightforward methodology is demonstrated through SPICE simulations which are based on a threshold-type device model for memristors. Overall, this work contributes to the creation of proper methodologies which will enable the development of efficient design flows for circuits and architectures comprising memristors. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The structural and electrophysical properties of titanium oxide based memristor obtained by pulsed laser deposition were analysed. The experimental results found the possibility of fine tuning of memristor active layers stoichiometry during deposition. In addition, the atomic force microscopy analysis of the surface of titanium oxide films revealed its high morphological homogeneity and continuity. The obtained memristors with gold contacts have been possessed bipolar switching mechanism and high endurance. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Radiation effects in solid nitrogen irradiated with an electron beam were studied with emphasis on the role of charged centers in radiation-induced phenomena. The experiments were performed employing luminescence method and activation spectroscopy techniques - spectrally resolved thermally stimulated luminescence TSL and thermally stimulated exoelectron emission. Samples were probed in depth by varying electron energy, thus discriminating radiation-induced processes in the bulk and at the surface. Spectroscopic evidence of the excited N2* (C3Πu) molecule desorption was obtained for the first time and mechanism of the phenomenon based on recombination of electron with intrinsic charged center N4+ was proposed. The key role of N3+ center dissociative recombination in generation of N radicals is suggested. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We obtained the two- and three-component nanostructures by means of ion implantation of low-energy Co and Ba ions in the surface layers of Si and GaAs in combination with the post-implantation annealing. We show that flat shaped nanocrystals (nanoislands) of two- and three-component composition, Co-Si and Ga-Ba-As, start forming at ion fluences of Φ = (6¸8)×1014 cm-2. After the laser annealing and short time electron heating we observed the formation of CoSi2 and Ga0.4Ba0.6As nanocrystals. Our results show that the size effects are clearly seen in electronic properties (opening of the band gap) when the lateral size of nanocrystals is less than 15-30 nm, or in case of solid nanofilms, similar effect is observed at the thickness less than 3-4 nm. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]