Papers by Keyword: Thermal Evaporation

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Authors: Hyoun Woo Kim, Ju Hyun Myung, S.H. Shim
Abstract: We have synthesized gallium oxide (Ga2O3) nanomaterials at two different growth temperatures on iridium (Ir)-coated substrates by thermal evaporation of GaN powders. The products consist mainly of nanobelts, with some additional nanosheets. The nanobelts were of a single-crystalline monoclinic Ga2O3 structure. The broad emission photoluminescence band of 900°C-products had a different peak position from that of the 970°C-products.
Authors: Chetan Zankat, V.M. Pathak, Pratik Pataniya, G.K. Solanki, K.D. Patel, Salil Nair, Jolly Mary Joy
Abstract: Amorphous SnSe thin films were deposited by thermal evaporation technique on glass substrates kept at room temperature in a vacuum better than 10-5Torr. A detailed study of structural and optical properties of 150 nm thin film was carried out. The selected area diffraction patterns obtained by TEM for this thin film were analyzed by a new method that involves accurate determination of lattice parameters by image processing software. The obtained results are in good agreement with the JCPDS data. Optical transmission spectra obtained at room temperature were analyzed to study optical properties of deposited thin films. It has been found that indirect carrier transition is responsible for optical absorption process in the deposited thin films.
Authors: S.H. Shim, Hyoun Woo Kim, C. Lee, D.J. Chung, S.G. Park, S.G. Lee, B.H. O, J. Kim, S.P. Chang, S.H. Lee
Abstract: We have obtained one-dimensional (1D) nanomaterials of tin oxide (SnO2) on silicon nitride (Si3N4)-coated Si substrates by carrying out the thermal evaporation of solid Sn powders and varying the substrate temperature in an Ar/O2 ambient gas. We analyzed the samples with scanning electron microscopy, X-ray diffraction, transmission electron microscopy and photoluminescence (PL). Reactions at a lower substrate temperature gave rise to thinner 1D structures. The obtained 1D nanomaterials were single crystalline with a tetragonal rutile structure. We proposed a vapor-solid process as the growth mechanism for SnO2 nanorods. The PL spectrum exhibited visible light emission.
Authors: Jing Lv
Abstract: Al films (about 40 nm) were prepared on quartz substrates by thermal evaporation technique, and subsequently annealed in air for 1h at temperature ranging from 600 to 1300oC. The characteristics of the annealed films were investigated in this paper. The measurement results of XRD and Raman show that crystalline phase transformations of the annealed films will convert from γ, γ and α, up to α-Al2O3 with the increasing of the annealing temperature at 600 oC, 1200 oC, to 1300oC. AFM and transmission spectra reveal the effects of phase transformations on their morphology and optical properties.
Authors: Hyoun Woo Kim, S.H. Shim, Ju Hyun Myung
Abstract: One-dimensional structures of tin oxide (SnO2) on TiN-coated substrates were obtained by simple heating of Sn powders. X-ray diffraction, high-resolution transmission electron microscopy, and the selected area electron diffraction showed that 1D structures are composed of SnO2 with rutile structure. The photoluminescence of the structures in the visible region suggests possible applications in nanoscaled optoelectronic devices.
Authors: G.H. Tariq, M. Anis-ur-Rehman
Abstract: Polycrystalline thin films of Cadmium Sulfide (CdS) have been extensively studied for application as a window layer in CdTe/CdS and CIGS/CdS thin film solar cells. Higher efficiency of solar cells is possible by a better conductivity of a window layer, which can be achieved by doping these films with suitable elements. CdS thin films were deposited on properly cleaned glass substrate by thermal evaporation technique under vacuum2×10-5mbar. Films were structurally characterized by using X-ray diffraction. The X-ray diffraction spectra showed that the thin films were polycrystalline in nature. Aluminum was doped chemically in as deposited and annealed thin films by immersing films in AlNO33.9H2O solutions respectively. Comparison between the effects of different doping ratios on the structural and optical properties of the films was investigated. Higher doping ratios have improved the electrical properties by decreasing the resistivity of the films and slightly changed the bandgap energy Eg. The grain size, strain, and dislocation density were calculated for as-deposited and annealed films.
Authors: C. Prabukumar, M. Jayalakshmi, K. Udaya Bhat
Abstract: ZnO nanostructures such as nanowires and nanorods are beneficial in solar energy harvesting because they provide a structure with a large surface area. Also, they provide a direct pathway to electron transportation, eliminating the scope for grain boundary scattering. In this investigation, thin ZnO films were prepared by thermal evaporation of the Zn metal, which was followed by oxidation. Evaporation parameters and oxidation temperatures were fixed. The oxidation duration was the variable. The effect of oxidation time, on the morphology and structural properties were studied by using scanning electron microscopy and X-ray diffractometry. The study shows that with increase in oxidation time, the morphology changed to nanorods from initial flake morphology. As a function of oxidation time, the crystallinity and texture became more dominant. By using, I-V characteristic curves, it was found that the morphology changes alter the surface electrical conductivity of the prepared ZnO films.
Authors: Priyanka Singh, Shailesh N. Sharma, G. Bhagavannarayana, M. Husain, M. Lal
Abstract: Porous silicon (PS) layers were formed by anodization on polished substrates of (1 0 0) Si at different current densities for a fixed anodization time of 30 mins. using different screenprinted/ evaporated back contacts (Ag, Al) respectively. The PS films has been characterized by high resolution X-ray diffraction (HRXRD), photoluminescence (PL), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) techniques respectively. Porosity and thickness of PS layers were estimated by gravimetric analysis. The properties of PS formed using screen-printed Ag & Al as the back contacts (SP-(Ag/Al)) was found to be superior as compared to the corresponding films with evaporated back contacts (EV-(Ag/Al)). The PS formed with screenprinted Ag & Al-back contacts shows better crystalline perfection, higher stability, higher PL efficiency and negligible PL decay compared to that formed with evaporated Ag & Al- as the back contact for the same current density and time of anodization.
Authors: Hong Jie Jia, Shu Ying Cheng, Pei Min Lu
Abstract: SnS and Ag films were deposited on glass substrates by vacuum thermal evaporation successively, and then the thin films were annealed at 260°C in N2 for different times (60min, 120min, 180min) in order to investigate the influence of annealing time on the silver-doped SnS (SnS:Ag) films. The obtained films annealed at different times are polycrystalline SnS with orthogonal structure, and the crystallites in the films are exclusively oriented along the {111} direction. With the increase of annealing time, the uniformity and crystallization of the films are improved, the carrier concentration and mobility of the films first rise and then drop, whereas their resistivity and direct bandgap energy Eg show the contrary trend.
Authors: Cheng Hsing Hsu, Ching Fang Tseng, Yi Ting Yu, Pai Chuan Yang, Chun Hung Lai, Jenn Sen Lin, His Wen Yang
Abstract: The electrical properties of evaporated ZnTe films were investigated with emphasis on the effects of an annealing temperature from 600oC to 800oC by RTA technique. Crystallinity, carrier concentration, sheet resistance, and mobility are shown to be dependent on the annealing temperature. The highest carrier concentration and lowest sheet resistance are 7.9×1015 cm-3 and 9300 Ω/□ at an annealing temperature of 700oC, respectively. The mobility was found to vary from 20 to 50 cm2V-1S-1. The ZnTe thin films using thermal evaporation can find applications in solar cell or light emitting diodes
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