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• Annealing improves Sb 2 Se 3 films' refractive index, absorptivity, and reduces the optical band gap. • Sb 2 Se 3 films crystallize from 200 °C, optimal grain size and fewer defects at 325 °C. • Excessive annealing turns Sb 2 Se 3 films from semiconductors into conductors. • EDS and Raman spectra reveal changes in film composition and atomic bonding. To achieve high conversion efficiency in Sb 2 Se 3 thin films, the effects of different annealing temperatures on the optical properties and microstructure were investigated. The experiment shows that annealing improves Sb 2 Se 3 films' refractive index, absorptivity, and reduces the optical band gap. The first-principle theoretical analysis reveals that defects in the films such as Sb Se2 , Sb Se3 , V Se2 , and V Se3 significantly affect their optical band gap. Based on the XRD (X-ray diffraction) patterns, the half-height widths, average grain sizes, microstrains and dislocation densities of the diffraction peaks have been calculated. The results show that the optimal annealing temperature is 325 °C. Finally, EDS (Energy Dispersive Spectrometer) and Raman spectroscopy were used to explain the reasons for the changes in the optical properties and internal structure of the film with the annealing temperature from the perspectives of the changes in the film components and the bonding properties between the atoms. [ABSTRACT FROM AUTHOR]

• non-crystalline Ge x Se 100- x (x = 15−25 at. %) films were obtained by evaporation in vacuum. • optical parameters (OPs) of the films depend on the Ge concentration. • abnormal dispersion of refractive indices n (λ) with n max was detected in ultraviolet. • the change in the position of n max is affected by the Ge concentration in the films. • nonlinear OPs χ(3) and n 2 of the films increase as Ge concentration decreases. Four non-crystalline Ge x Se 100− x (x = 15−25 at. %) films were obtained by vacuum-thermal deposition of glassy Ge–Se alloys. With the use of spectroscopic ellipsometry, it was determined that the films are semiconductors with indirect band gap energy E g = 2.0−2.07 eV. An anomalous dispersion of the refractive index n (λ) with n max at λ max depending on x was revealed in the films at λ = 240−500 nm. It was established that as the concentration of Ge decreases, n max increases, and λ max red shifts. Based on the Wemple-DiDomenico model, the nonlinear coefficients χ(3) and n 2 characterizing the synthesized films were calculated as a function of x. The highest χ(3) and n 2 values are achieved in the films at x = 15 at. %. The results obtained can be used for the development and creation of Ge–Se optical filters with an adjustable blue absorption band edge. [ABSTRACT FROM AUTHOR]

Fabrication of Ge x C 1 − x has been a big challenge because of the solubility of C in Ge. Only a small percentage of Ge C bonds (11.6%) have been introduced so far. In this work, a-Ge x C 1 − x with GeC content up to 21% has been fabricated with 50 W RF power at 250 °C by reactive sputtering methods. The effects of the radio frequency power and substrate temperature on the yield of GeC were analysed in detail. The GeC percentage by volume was found to first increase and then decrease with increasing substrate temperature. Introduction of C into the Ge matrix seems to tune the optical bandgap over a range of 2.7 eV to 1.0 eV depending on the combination of substrate temperature and radio frequency power. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effect of post-annealing on the electrical properties of amorphous gallium-zinc-tin oxide (a-GZTO) films with different Ga contents. The films were deposited at room temperature by sputtering and annealed in air for 1h. It was found that the doping with Ga, which acts as the carrier suppressor, contributes to the thermal stability of characteristic properties of a-GZTO thin films. The film with a small amount of Ga showed significant variations in carrier concentration according to the annealing temperature. Increases in carrier concentration and mobility can be ascribed to the reduction of subgap density of states by annealing. After annealing at 400°C, however, the enrichment of Zn cations in surface region resulted in considerable changes in chemical bonding states and consequently, the carrier concentration decreased by two orders of magnitude for the low Ga-doped ZTO film. [Copyright &y& Elsevier]

Abstract: Electrodeposition of Cu layers on a Mo-coated glass (Mo/glass) substrate from CuSO4 solutions containing citric acid and sodium citrate was studied for fabrication of CuInS2-based solar cells. When the deposition was performed using the CuSO4 solution containing citric acid, a Cu layer consisting of less-compact roundish grains with a rugged surface morphology was obtained. On the other hand, a compact Cu layer composed of large angular grains was formed from the CuSO4 solution containing sodium citrate. Electrochemical studies revealed that both organic additives worked as complexing agents to reduce the concentration of free Cu2+ ions, but complexation abilities of these additives were different, leading to the structural difference in the resulting Cu layers. The CuInS2 film derived from the former less-compact Cu layer had good adhesion between the CuInS2 film and Mo/glass, whereas the CuInS2 film obtained from the latter compact Cu layer was partially exfoliated because of large volume expansion stresses during the transformation of Cu and In stacked layers into the CuInS2 film. As expected from these differences, the solar cell with an Al:ZnO/CdS/CuInS2/Mo/glass structure derived from the former less-compact Cu layer showed better properties than those of the solar cell derived from the latter compact Cu layer. [Copyright &y& Elsevier]

Abstract: The low temperature deposition of photoconductive InXGa1-XN films was carried out by simultaneous reactive rf- magnetron sputtering. In the films deposited using Ga and In targets, XRD peaks corresponding to wurtzite InXGa1-XN were observed. The optical band gap energy decreased from 3.27eV to 1.63eV with increasing the In composition ratio X =In/(Ga+In) from 0 to 0.58. The N composition ratio N/(Ga+In) and photosensitivity of the film with the optical band gap energy of 2.09eV were 0.68 and 1.89, respectively. In order to improve the photosensitivity, GaN and InN targets were used instead of Ga and In targets. The N/(Ga+In) and photosensitivity of the film with the optical band gap energy of 2.08eV deposited using GaN and InN targets were 0.86 and 252, respectively. [Copyright &y& Elsevier]

Abstract: In this work we present a comparative study on the electrical characteristics of polymorphous silicon (pm-Si:H) and polymorphous germanium (pm-Ge:H) thin films deposited by low frequency plasma enhanced chemical vapor deposition (LF-PECVD), aiming to use them as thermo sensing elements in un-cooled microbolometers. We studied the effect of the deposition pressure on the film characteristics that are important for IR detection, as the activation energy (Ea), the thermal coefficient of resistance (TCR), the room temperature conductivity (σRT) and the film responsivity with IR radiation. Our results indicate that polymorphous films have advantages over boron doped a-Si:H, material which is currently employed as thermo-sensing element in commercial microbolometer arrays. [Copyright &y& Elsevier]

Abstract: In this work is presented the fabrication of a thin film membrane as a bio-transducer for aural assistance detection, therefore it will operate at low pressure. The resonant membrane was deposited by PECVD technique at low temperature of deposition T=270°C, using SiH4, GeH4, and Boron gases. The membrane was suspended on a micromachined crystalline silicon frame obtained by wet chemical etching. The a-SiGe:B film presented a resistivity of 2.46×103 (Ω-cm), resistance of 20.8kΩ. Using these experimental data we succeeded in designing a simple structure for sensing low pressure variations. The output voltage of the sensor was measured for a range of pressure from 0 to 3000Pa and at bias voltage of 10V. [Copyright &y& Elsevier]

Abstract: In this work, the effect of hydrogen dilution on the Ge content of the film and the effect of bandgap grading in the a-Si1−xGex:H absorber near the p/i and the i/n interfaces on cell performance were discussed. The a-Si1−xGex:H single-junction solar cells were improved by employing both p/i grading and i/n grading. The i/n grading increased the VOC and the FF while it also reduced the JSC as compared to the cell without grading. Presumably the potential gradient established by the i/n grading facilitates the hole transport hereby improved by the FF. On the contrary, the potential barrier established by the p/i grading seemed to limit the cell performance and constrain the p/i grading width below 20nm due to the drop in FF and JSC. Combining the effects of bandgap grading on the VOC, JSC and FF, the suitable thicknesses of the p/i and the i/n grading were 20nm and 45nm, respectively. Finally, the grading structures accompanied with further optimization in doped layers were integrated to achieve a cell efficiency of 8.59%. [Copyright &y& Elsevier]

Abstract: We have studied the epitaxial-like growth of germanium (Ge), due to solid phase crystallization (SPC) from amorphous Ge (a-Ge) deposited on single crystal silicon (Si) substrate. The crystalline growth of Ge following the orientation of Si substrates was successfully obtained by the SPC at 400°C or higher. The preferential growth on Si (111) substrates continues up to 10,000Å. Different orientations from the substrate orientation in XRD patterns are slightly observed in the growth on Si (100) substrates at 450°C, but the preferential growth of (100) orientation continued in the whole film thickness in TEM images. The epitaxial-like growth of Ge may be more preferable on the Si (111) substrate than the (100) one. [Copyright &y& Elsevier]

Abstract: The superlattice films, which consist of amorphous silicon (a-Si) and amorphous gold (Au), were prepared by ultra-high vacuum evaporation system. The first layer was grown a-Si with a thickness of 4.2nm and the second layer was grown Au with a thickness of 0.8nm. Thermal annealing was performed at 473, 673, and 873K, respectively. The structural properties of the films were investigated using transmission electron microscope (TEM), X-ray diffraction (XRD), and Raman scattering spectroscopy. The electrical property was assessed by the temperature dependence of electrical conductivity. A crystallization of Si and a forming of Au nanoparticles were observed in all of the annealing films. The crystalline volume fraction reached 70% by annealing time for 15min. An average diameter of the Au nanoparticles embedded in Si matrix also increased with increasing the annealing temperature. At annealing temperature above 873K, Au atoms migrated toward the film surface. It was observed that the electrical conductivity changed in several temperatures. [Copyright &y& Elsevier]

Abstract: Si quantum dots (Si QDs) films were prepared by annealing amorphous SiC single layer and amorphous Si/SiC multilayers fabricated in plasma enhanced chemical vapor deposition system. The microstructures were characterized by Raman spectroscopy as well as Fourier transforms infrared spectroscopy for both samples. It was found that Si QDs with average size of 2.7nm were formed after annealing and the electroluminescence (EL) band centered at 650nm can be observed at room temperature. The EL intensity from the Si/SiC multilayers was obviously improved by one order of magnitude and the corresponding EL band width was reduced compared with that from SiC single layer film. The improved electroluminescence behavior can be attributed to the formation of the denser Si QDs, good size distribution and the strong confinement effect of carriers in multilayerd structures. [Copyright &y& Elsevier]

Abstract: We present the results of investigations on a variety of stoichiometric μc-SiC:H films deposited by Hot-Wire- and Plasma-Enhanced Chemical Vapour Deposition using monomethylsilane diluted in hydrogen as precursor gas. Infrared spectroscopy, grazing incidence X-ray diffraction, and Transmission Electron Microscopy were applied and compared to separate the contributions from the different structure phases of the material. It is shown that an evaluation of the crystalline volume fraction from the infrared absorption lineshape of the Si–C stretching mode is not possible, although stated in the literature. A correlation of this lineshape with the material strain is proposed. Moreover, a variation in strain, grain size, and structural defects is found depending on the deposition conditions, but a mixture of an amorphous and a crystalline phase could not unambiguously be identified. [Copyright &y& Elsevier]

Abstract: Thin films of tin sulphide (SnS) were deposited on tin oxide conducting glass substrates by thermal evaporation technique. The transmission spectrum of the SnS film in the wavelength range from 300 to 1100nm has been obtained. X-ray diffraction has been used to determine the structure of the films. The film thickness and refractive index have been estimated from the transmission spectra. The results showed that the refractive index of the SnS thin films is thickness independent in the wavelength range 590≤ λ ≤1100nm and found to be ~1.72. This result indicates that the SnS thin films are homogeneous and isotropic. The energy band gaps were found to be between 1.06 and 1.32eV, which is in good agreement with literature values. The energy dependence of the obtained refractive index is also investigated. [Copyright &y& Elsevier]

Abstract: The change in the surface morphology of amorphous Sb2Se3 thin films during the electron beam irradiation has been studied mainly by atomic force microscopy (AFM). Electron beam at accelerating voltages 30kV is focused onto the surface of the specimens of 100-μm thickness, and then the surface morphology of each specimen has been observed by AFM in air. The modification of the film surface includes lateral and vertical resizing which is typically in the micrometer and sub-micrometer range. Protrusions above the surface as high as 90nm are observed at 180pA electron beam current, whilst trenches as deep as 97nm are observed at 800pA electron beam current (total thickness of thin film is 100nm). The dependence of patterns characteristics on irradiation parameters such as exposure time and beam current has also been studied. Physical mechanisms for trench and mound formation are proposed. [Copyright &y& Elsevier]

Abstract: In this work, a study of aluminum induced crystallization (AIC) of thin film germanium/silicon/aluminum (Ge/Si/Al) structure on oxidized silicon is presented. The Ge/Si/Al trilayer structure was prepared in three consecutive thin film deposition processes. The AIC was performed in nitrogen at 500°C within time duration between 1 and 9h. The progress of crystallization was monitored by optical microscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). It was found that in Ge/Si/Al structure the AIC can lead to formation of SiGe alloy at temperature of 500°C. This presents an alternative low-temperature formation method of SiGe which is suitable for integration with the conventional Si technology in electronic device fabrication. [Copyright &y& Elsevier]

Abstract: Tin-doped NiO thin films (5.0, 7.4, and 9.3at.% Sn) have been prepared by thermal oxidation of vacuum deposited films of pure Ni and Sn elements on glass and silicon substrates. The prepared films were comprehensively characterised by X-ray fluorescence, X-ray diffraction, UV–VIS-NIR absorption spectroscopy, and electrical (ac and dc) measurements. Experimental data indicate that Sn4+ doping slightly stress the host NiO crystalline structure and change the optical and electrical properties. The electrical and optical behaviours of the Sn-doped NiO films show that they are wide-band semiconductors with band gap 3.69–3.76eV and have insulating properties. The ac and dc electrical measurements show that it is possible to use Sn-doped NiO as an optical-sensitive oxide in metal-oxide-silicon configurations. [Copyright &y& Elsevier]

Abstract: In the present paper, we report about synthesis of nanostructured organic–inorganic heterojunction of CdS/Polyaniline/CuInSe2 thin films by cost effective chemical route at room temperature, for solar cell application. As such obtained thin films are characterized for structural, compositional, morphological, optical and electrical properties by X-ray diffraction (XRD) pattern, energy dispersive X-ray (EDAX) analysis, scanning electron microscopy (SEM), optical absorbance spectra and I–V response respectively. The XRD reveals the polycrystalline nature of the thin films having tetragonal crystal structure and a crystallite size of 19nm. The presence of observed and expected elements in the EDAX spectra confirms the elemental compositions in CdS/Polyaniline/CuInSe2 thin films. From SEM images it can be inferred that the surface morphology of the Polyaniline thin films exists like clothing fibers, while CdS/CuInSe2 shows granular shape particles distributed over the substrate and the SEM of CdS/Polyaniline/CuInSe2 represents mixing and attachment of circular particles to fiber like structure. The optical absorbance spectra have shown red shift in absorbance strength and energy band gap value of CdS/CuInSe2 from ~1.36eV to ~1.62eV upon formation of CdS/Polyaniline/CuInSe2 thin film. The I–V response of CdS/CuInSe2 and CdS/Polyaniline/CuInSe2 measured under dark and illumination to 100mW/cm2 light, exhibited the solar characteristics from these graphs and the conversion efficiency calculated is observed to be 0.26 and 0.55% for CdS/CuInSe2 and CdS/Polyaniline/CuInSe2 thin films respectively. [Copyright &y& Elsevier]

Abstract: The processes of charge transport and trapping in amorphous Si1− x C x :H films deposited on crystalline p-type Si wafers and annealed in vacuum in the temperature range 300–650°C have been evaluated. Current–voltage (I–V), capacitance–voltage (C–V) and admittance–temperature (G–T) characteristics were measured in the temperature range 100–350K. The spectrum of thermal effusion of hydrogen was measured from room temperature up to 1000°C. C–V characteristics indicate a slight increase of the dielectric constant k and a large hysteresis after annealing at 450°C. The hysteresis is believed to be associated with mobile hydrogen effusion from the a-SiC:H film, and it is not seen after a 650°C anneal. From I–V data the maximum rectification ratio is observed after annealing at 450°C. Variable-range hopping (VRH) conduction at the Fermi level is found to dominate the forward current of the as-deposited structure. After annealing at 450°C the forward current can be described by space-charge limited (SCL) mechanisms with trapping at shallow levels with energy of about 0.12eV. After annealing at 650°C the process of VRH conduction appears again, but the density of hopping sites is much higher than in the as-grown sample. From admittance spectra, the energy position of respective traps in a-SiC:H is at (E V +0.45) eV for as-deposited material and it decreases slightly after vacuum annealing. On the basis of these results, an energy band diagram of the a-Si1− x C x :H/p-Si structure annealed at 450°C is proposed. [Copyright &y& Elsevier]

Abstract: The electrical switching behavior of amorphous Al23Te77 thin film devices, deposited by flash evaporation, has been studied in co-planar geometry. It is found that these samples exhibit memory type electrical switching. Scanning Electron Microscopic studies show the formation of a crystalline filament in the electrode region which is responsible for switching of the device from high resistance OFF state to low resistance ON state. It is also found that the switching behavior of thin film Al–Te samples is similar to that of bulk samples, with the threshold fields of bulk samples being higher. This has been understood on the basis of higher thermal conductance in bulk, which reduces the Joule heating and temperature rise in the electrode region. [Copyright &y& Elsevier]

Abstract: Photoconductivity (PC) variations of device-grade a-Si:H thin films due to proton irradiation are investigated in this paper. We performed in-situ measurements of the PC variations induced by 0.10, 1.0 and 10MeV proton irradiations. The irradiation initially caused an increase in PC in all sample. However, continued irradiation resulted in a dramatic decrease as the irradiation fluence increased. The results obtained in this study suggest that the PC increment is caused not by accumulation of displacement damage. We also found that the dark conductivity (DC) was drastically increased in the same manner as the PC increment, whereas the photosensitivity had a minimum value at the peak of the PC increment. The results of the temperature dependence of PC for a-Si:H before and after 10MeV proton irradiation showed that such a proton-induced PC increment consisted of two components: one thermally stable and one metastable. The thermally metastable component disappeared in the temperature region of 300 to 340K. On the contrary, radiation-induced defects were annealed above 340K. [Copyright &y& Elsevier]

Abstract: A novel process is employed in the fabrication of porous anodic aluminum oxide film in neutral electrolyte. A titration technique which involves titration of acid–base neutralization process is used as the electrolyte source in the anodization of the aluminum substrate. Freshly prepared 10% phosphoric acid at pH1 is titrated with 1M of sodium hydroxide until it reaches pH7 in a neutral environment. The growth of the porous anodic film was made possible by 60V dc applied potential from an in-house electrochemical cell to the aluminum substrate in the neutral electrolyte. The diameter of the pores produced is in the range of 40–200nm. [Copyright &y& Elsevier]

Abstract: Zn–O–Se alloy films were grown on quartz substrate by radio-frequency (rf)-magnetron sputtering ZnSe single crystal target, with high pure Ar and O2 as working gas. X-ray diffraction and transmission electron microscopy characterizations indicate that the films are amorphous state. Energy disperse spectroscopy and X-ray photoelectron spectroscopy measurements verify the amorphous Zn–O–Se alloy was Se doped ZnO2 (Zn1− x Se x O2), in which both Zn and Se atoms are bound with O atom. Absorption spectra exhibit that the optical band gap of Zn1− x Se x O2 films are 4–5eV. After annealing at 673K in Ar ambient for 15min, Zn1− x Se x O2 film was decomposed to ZnO and SeO2, and SeO2 sublimed while annealed. The band gap energy decreased to the 3.2eV, which is similar to the value of ZnO film directly deposited on quartz substrate. Room-temperature photoluminescence spectrum of the film after annealed shows NBE emission at 3.26eV. [Copyright &y& Elsevier]

Abstract: Phase transition triggered by picosecond (ps) single-shot laser pulse in as-deposited AgInSbTe films was achieved with appropriate laser fluence. Structure transition is further conformed by micro-area X-ray diffraction measurement. Current–voltage curves of the amorphous and the picosecond laser-crystallized area were measured by conductive atomic microscopy. Ultrafast laser pulse recording and electrically reading will be very promising for phase change data storage due to high data transfer rate and high readout signal-to-noise ratio. These results will be helpful to make ultrafast optical–electrical hybrid phase change data storage feasible. [Copyright &y& Elsevier]

Abstract: Si2Sb2Te5 alloys have potential applications for future chalcogenide random access memory (C-RAM). The thermally induced crystallization process of Si2Sb2Te5 alloys was characterized by in situ heating experiments with transmission electron microscopy (TEM). The crystallization of a Si2Sb2Te5 amorphous film was initiated at around 160°C, concomitant with a phase separation process. The crystallized product of the amorphous Si2Sb2Te5 film was a nano-scale (10nm in local-domain size) composite material consisting of amorphous Si (a-Si), crystalline Sb2Te3 (c-Sb2Te3) and crystalline Te (c-Te). [Copyright &y& Elsevier]

Abstract: The crystalline samples of Ge4Sb4Te10, Ge4Sb4Te9, and Ge4Sb4Te8 were prepared and their amorphous semiconducting thin films obtained by flash evaporation. Their sheet resistance decreased slowly with temperature up to 147–160°C with activation energy of electrical conductivity ΔE =0.40–0.44eV. Above these temperatures, the sheet resistance drops abruptly by several orders due to crystallization. The drop of resistivity proceeds in two steps. Two steps of phase change were also found on curves of DSC and on the temperature dependence of index of refraction. It pays for slow heating rates, crystallization induced by short (≈30ns) laser pulses proceeds probably in one step only for all studied samples (as it follows from X-ray diffraction), not only for Ge2Sb2Te5 in which a single phase formation was confirmed. The crystallization temperatures are increasing slightly with decreasing Te content in the series Ge4Sb4Te10–Ge4Sb4Te9–Ge4Sb4Te8 from 147 to 160°C. The X-ray diffractograms revealed that in laser crystallized samples can be found only cubic modification of Ge2Sb2Te5 type (a =0.6nm), while the samples annealed (230°C, 2h) or annealed after the crystallization with laser pulse, contain also small amounts of hexagonal phase. [Copyright &y& Elsevier]

Abstract: The role of the composition and of the related changes of the structure in the formation of the surface of amorphous As x Se1− x (0< x <0.5) layers before and after light treatment was investigated by direct measurements of the surface roughness at nanometer-scale and surface deformations at micrometer-scale under influence of illumination. It was established that the surface roughness of the films, deposited by vacuum thermal evaporation, decreased with increasing As content, especially in compositions 0.1⩽ x ⩽0.3, where the maximum light stimulated surface deformations (localized expansion) occurs. Both relate to the rigidity percolation range and the maximum photoplastic effects, which are not directly connected to the known photodarkening effect, since it is minimal for these compositions. [Copyright &y& Elsevier]

Abstract: A previews study of germanium selenide glass films by scanning electron microscopy and atomic force microscopy revealed a heterogeneous surface morphology consisting of granular regions ∼15–50nm in size, which cause high optical losses. The present work was performed in order to further characterize such materials using spectroscopic ellipsometry, infrared (IR) and Raman spectroscopies. Chalcogenide glass films with GeSe2, Ge28Sb12Se60 and GeSe compositions have been deposited on single crystal silicon and silica glass substrates by vacuum thermal evaporation. The film thickness and the optical constants were obtained from spectroscopic ellipsometry using the Tauc-Lorenz dispersion formula. A model was derived for the film structure, which included a roughness layer at the surface. This top layer was found to have a thickness of ∼5–15nm, of the order of the size of the granular regions previously reported. The optical bandgap of the samples increased with increasing selenium content, while the refractive index decreased. Despite a previous report of large scale phase separation in bulk Ge26Sb14Se60 glass, the fundamental IR and Raman spectra obtained in the present work did not provide any clear evidence for such phase separation which could be associated with the heterogeneous nanostructure observed at the surface of the films. [Copyright &y& Elsevier]

Abstract: Thin amorphous films of Ge–Sb–Te were deposited from Ge2Sb2Te5 target by RF (f =13.56MHz) magnetron sputtering in argon plasma. Composition and chemical homogeneity of target and prepared thin films were traced by Energy Dispersive X-ray Analysis coupled with Scanning Electron Microscope (SEM-EDX). SEM technique was also used for surface morphology observation. Crystallinity of target and prepared thin films was studied by X-ray Diffraction (XRD). Optical parameters of prepared thin films (spectral dependence of refractive index, optical band gap energy ) and film thicknesses were established via Variable Angle Spectroscopic Ellipsometry (VASE) supported by UV–Vis–NIR spectroscopy. Influence of deposition conditions (RF power, Ar pressure, angle divergency from normal direction) to composition, crystallinity, optical properties and deposition rate was established. [Copyright &y& Elsevier]

Abstract: Thin films of Ag photo-doped-Ge y Se1− y films were prepared by RF co-sputtering technique. A systematic study of the relation existing between the host layer composition and the saturation rate in silver was carried out. Morphology and composition studies before and after chemical etchings were performed by scanning electron microscopy and electron probe micro-analyses, respectively. Raman spectroscopy studies showed the presence of corner-sharing and edge-sharing Ge(Se1/2)4 tetrahedra in all thin films. The vibration mode corresponding to Se n -chains is observed for the Ge-poor host layer and on the contrary, Ge-rich thin films exhibited some tendency to form homopolar Ge–Ge bonds as a part of ethane-like Ge2Se6 units. These investigations revealed the amount of Ag that could be incorporated in the host layer. Such an amount strongly depends on the relative ratio Ge/Se in the Ge y Se1− y thin film. For the Ge-poor host layer, an incorporation of Ag (54at.%) was observed but also a drastic increase in the film heterogeneity. On the other hand, the host layers with higher Ge content showed homogeneous surfaces and a saturation level of ∼32–41at.%Ag. [Copyright &y& Elsevier]

Abstract: Thin amorphous films from system (As2Se3)80− x (As2Te3) x (SnTe)20 were prepared by pulsed laser deposition (PLD) from their bulk glasses and their optical properties were studied by spectral ellipsometry. Spectral dependencies of refractive index, absorption and extinction coefficient and optical gap (1.41–1.66eV for (As2Se3)80− x (As2Te3) x (SnTe)20 with x =20 resp. x =0) were calculated from optical tansmittance, from ellipsometric data by Tauc method. High values of refractive index n 0 (2.49–2.60) and of non-linear χ(3) coefficient of index of refraction (4.9–7.5×10−12 esu for the glass (As2Se3)80− x (As2Te3) x (SnTe)20 with x =0 resp. x =20) made studied thin films of system (As2Se3)80− x (As2Te3) x (SnTe)20 promising candidates for application in optics and optoelectronics. [Copyright &y& Elsevier]

Abstract: The optical and structural properties of Ge20Se80, Ge25Se75 and Ge30Se70 bulk glasses and Ag x (Ge0.20Se0.80)100− x thin films, where x =0, 6, 11, 16, 20 and 23at.% were studied. All samples were confirmed as amorphous according to XRD. The Raman spectra showed increase in 260cm−1 and 237cm−1 and decrease in 198cm−1 and 216cm−1 bands with different Se content in the bulk samples. The optical bandgap energy of bulk samples decreased (2.17–2.08eV) and refractive index increased (2.389–2.426 at 1550nm) with increasing Se content in bulk glasses. The Ge20Se80 thin films were prepared by vacuum thermal evaporation from Ge30Se70 bulk glasses. The Raman spectra of the films showed that peaks at 260cm−1 and 216cm−1 decreased their intensities with increasing Ag content in the thin films. The significant red shift of bandgap energy occurred upon different Ag content. The optically induced dissolution and diffusion resulted in graded refractive index profile along the film thickness caused by different Ag concentration. The refractive index increased from the substrate side to the top of thin films. The graded profile was getting more uniform with increasing content of silver in the thin film. [Copyright &y& Elsevier]

Abstract: X-ray photoelectron spectroscopy and depth profile analysis were used to investigate the X-ray-induced silver photodiffusion into an amorphous As50Se50 thin film. At the initial stages of irradiation an induction period was observed while core level spectra analysis revealed the existence of a mixed As–Se–Ag interlayer between the metal and the chalcogenide matrix. It was found that during the induction period this interlayer is enriched in silver and the existing As–Se–Ag intermediate species are transformed to Ag–Se–Ag that form the metal source for the effective silver photodiffusion. With further irradiation photodiffusion proceeds by the disruption of Ag–Se bonds and the recombination of As atoms with Se to stable As–Se units. Ultimately, silver concentration reaches a plateau when the diffusion stops. A separated Ag2Se phase on the film’s surface is identified at this stage. Depth profile analysis shows that silver has been homogenously diffused into the chalcogenide matrix and the Ag2Se phase exists only at the top surface layers probably in the form of quasi-crystalline clusters that prohibit further Ag diffusion. [Copyright &y& Elsevier]

Abstract: CdTe thin films were prepared onto water-white glass substrates by the close spaced sublimation technique. The films annealed right after the deposition were then immersed in copper nitrate solution for different periods of time. These films were again annealed at 500 oC for 1h to ensure the diffusion of copper in the films. The samples were characterized by X-ray diffraction and scanning electron microscopy. The electron microprobe analyzer showed an increase of copper-content in composition. The dc electrical conductivity showed a credible increase with increasing copper-content in the films. With the increase of copper-content, the hole mobility increased systematically. The optical parameters were deduced by fitting the optical transmittance in the wavelength range 300–2500nm. [Copyright &y& Elsevier]

Abstract: The atomic structure of amorphous As2Se3 and As2S3 films prepared by thermal evaporation in a vacuum and by RF ion-plasma sputtering has been studied by the methods of X-ray diffraction and Raman spectroscopy. The techniques of film preparation had different conditions of substance vaporization and atom condensation on a substrate. It has been established that films prepared by these methods have significant differences in the dimensions of the medium-range order and in the local atomic structure, which causes considerable differences in their electronic properties. [Copyright &y& Elsevier]

Abstract: Since the time sol–gel was suggested as a nonmelting technique for the preparation of glasses, an enormous amount of work has been done, moving from the more traditional glasses to new materials. Among these, hybrid organic–inorganic materials are of particular interest, not only for the amount of the applications they may be used for, but also because of their structural characteristics: hybrids are a mix, at molecular level, of inorganic and organic moieties, where the organic ones may be simply dissolved in the matrix or behave as network former or modifier. The most recent results on the synthesis of this type of films, obtained by the author and co-workers, will be presented and discussed. In particular, the focus will be on the possibility to control the structural development by acting on the organic and inorganic polymerization separately and the challenges that this approach offers. [Copyright &y& Elsevier]

Abstract: Transparent undoped semiconductor indium oxide films were deposited by radio frequency (rf) plasma enhanced reactive thermal evaporation (rf-PERTE) of indium at low substrate temperature. It was experimentally verified that the variation of rf power density has a strong influence on the electrical and structural properties of the films. The thickness of the InO x films is of about 100nm. Results show that InO x films show an average visible transmittance of about 85% and energy gap of about 2.6eV. Structural and electrical conductivity measurements show that films are polycrystalline and there exists a linear variation of conductivity logarithm vs reciprocal of temperature. Electrical conductivity variation of 17.6 to 5.8×10−3 (Ω cm)−1 for films produced at rf power densities ranging from 3.9 to 78.1mWcm−3 was obtained. This controllable semiconductor behavior can therefore satisfy the requirement of a particular application for these type of films. [Copyright &y& Elsevier]

Abstract: Ge nanodots, produced by solid phase crystallization of amorphous Ge layers deposited at room temperature on SiO2 thermally grown on a Si(100) surface, generate a photocurrent in the visible and ultraviolet range. The photocurrent signal was detected by measuring the current flowing through the sample under irradiation either in planar or in up-down geometry. In both cases the quantum efficiency of the bare SiO2/Si(100) substrate was dramatically enhanced up to a factor of 103. Current–voltage curves were acquired in the latter geometry, evidencing an increase in the short circuit current induced by the Ge nanodots presence. [Copyright &y& Elsevier]

Abstract: Transparent, undoped semiconductive thin films of zinc oxide were deposited by radio frequency plasma enhanced reactive thermal evaporation of zinc rods in the presence of oxygen at room temperature, without any post-deposition annealing treatments. The study of the variation of rf power, in the range 5–200W, on the main properties of these films was made. A decrease of the electrical conductivity of these films with increasing rf power was observed (10−3 to 10−12 (Ωcm)−1), respectively, while the average visible transparency was kept practically constant (≈80%). From this initial study, a set of bottom-gate type thin-film transistors were made using the most promising semiconductor materials. Preliminary I(V) measurements showed all transistors working, with best results obtained from zinc oxide material deposited at the lowest rf power (20W), within the deposition conditions range which leads to semiconductive material. Such devices presented an I on (20V)/I off (−5V) ratio of 6×106 and a field-effect mobility of 0.37cm2/(Vs). [Copyright &y& Elsevier]