Author
R. Pal
Bio: R. Pal is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Grain boundary & Thin film. The author has an hindex of 8, co-authored 14 publications receiving 187 citations.
Papers
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TL;DR: CulnSe2 films with different Cu/In ratios (0.4-1.2) were deposited on glass substrates by three source evaporation techniques in this paper.
Abstract: CulnSe2 films with different Cu/In ratios (0.4–1.2) were deposited on glass substrates by three source evaporation techniques. The films were polycrystalline in nature with partially depleted grains. Photoconductivity in the films was measured in the temperature range 170–370 K. The data at low temperatures (T
34 citations
TL;DR: The shift of the band gap to higher energies depended on the relative magnitudes of substrate temperature and gas pressure during deposition as mentioned in this paper, and the relative magnitude of temperature and pressure during the sputtering of a ZnTe target was determined.
Abstract: ZnTe films in nanostructured form have been deposited by high pressure d.c. magnetron sputtering of a ZnTe target onto different substrates kept at various temperatures ranging from 223–373 K. Shift of the band gap to higher energies depended on the relative magnitudes of substrate temperature and gas pressure during deposition.
24 citations
TL;DR: In this article, nanocrystalline ZnSe films were deposited onto glass, quartz and NaCl substrates by sputtering of a znSe target in argon plasma and optical, microstructural, and photoluminescence studies were carried out in order to understand the quantization effect, along with optical absorption and emission processes, in the material in nanocrystine form.
Abstract: Nanocrystalline ZnSe films were deposited onto glass, quartz and NaCl substrates by sputtering of a ZnSe target in argon plasma. Optical, microstructural, and photoluminescence studies were carried out in order to understand the quantization effect, along with optical absorption and emission processes, in the material in nanocrystalline form. © 1997 Acta Metallurgica Inc.
16 citations
TL;DR: In this paper, Schottky diodes of structure Au/nano-CdS/CBD-CDS/SnO 2 were fabricated with the nanocrystalline CdS layer deposited by the high pressure magnetron sputtering technique.
Abstract: Schottky diodes of structure Au/nano-CdS/CBD-CdS/SnO 2 were fabricated with the nanocrystalline CdS layer deposited by the high pressure magnetron sputtering technique. The devices were characterized by current-voltage (I-V) anti capacitance-voltage (C-V) measurements. It was observed that the presence of a large amount of surface states might explain the high values of n in the nano-devices. The quantization effects of the active nano-CdS layer in the devices was confirmed from the observed peaks in the plot of conductance versus reverse bias voltage.
15 citations
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Journal Article•
TL;DR: In the limit of a QD much smaller than the bulk exciton size, the linear spectrum will be a series of lines, and the phonon broadening of these lines is considered.
Abstract: We analyze theoretically the optical properties of ideal semiconductor crystallites so small that they show quantum confinement in all three dimensions [quantum dots (QD's)]. In the limit of a QD much smaller than the bulk exciton size, the linear spectrum will be a series of lines, and we consider the phonon broadening of these lines. The lowest interband transition will saturate like a two-level system, without exchange and Coulomb screening. Depending on the broadening, the absorption and the changes in absorption and refractive index resulting from saturation can become very large, and the local-field effects can become so strong as to give optical bistability without external feedback. The small QD limit is more readily achieved with narrow-band-gap semiconductors.
788 citations
TL;DR: In this article, ZnSe nanoparticles of about 3 nm in size have been prepared by the sonochemical irradiation of an aqueous solution of selenourea and zinc acetate under argon.
Abstract: ZnSe nanoparticles of about 3 nm in size have been prepared by the sonochemical irradiation of an aqueous solution of selenourea and zinc acetate under argon. The ZnSe nanoparticles were characterized using techniques such as transmission electron microscopy, X-ray diffraction, absorption spectroscopy, differential scanning calorimetry, transmission and diffuse reflection spectroscopy, photoluminescence spectroscopy, and energy-dispersive X-ray analysis. The mechanism of the sonochemical irradiation is discussed. This sonochemical method was found to be a general method for the preparation of other selenides as well.
194 citations
TL;DR: In this article, the optical properties of thermally evaporated and laser annealed ZnSe thin films were investigated in the spectral range 300-2500nm at room temperature.
Abstract: This research work is devoted to the study of optical properties of thermally evaporated and laser annealed ZnSe thin films. Thin films of zinc selenide were annealed by a CO2 pulsed laser at different powers (10, 20 and 30 Watt). As shown by X-ray diffraction analysis, all the studied films exhibit cubic zinc blende crystal structure with dominant preferred orientation along the plane (111). Optical transmission spectra, were investigated in the spectral range 300–2500 nm at room temperature. Swanepoel’s envelope method was employed to check the film thicknesses, as well as to evaluate the refractive index, absorption coefficient and the extinction coefficient by using transmission measurements only. Optical energy gap was determined using Tauc plot extrapolation. It was found to be increased from 2.67 to 2.90 eV with increasing the pulsed laser annealing power and it is due to allowed direct transition. Using Wemple-DiDomenico single oscillator model, the dispersion of the refractive index and energy dispersion parameters together with their dependences on the laser annealing power have been studied.
141 citations
TL;DR: In this article, thin films of ZnSe were deposited on soda lime glass substrates by thermal evaporation and annealed in vacuum at various temperatures in the range of 100-300°C. Structural and optoelectronic properties of these films were investigated and compared with the available data.
Abstract: Thin films of ZnSe were deposited on soda lime glass substrates by thermal evaporation and annealed in vacuum at various temperatures in the range of 100–300 °C. Structural and optoelectronic properties of these films were investigated and compared with the available data. XRD studies revealed that as-deposited films were polycrystalline in nature with cubic structure. It was further observed that the grain size and crystallinity increased, whereas dislocations and strains decreased with the increase of annealing temperature. The optical energy band gap estimated from the transmittance data was in the range of 2.60–2.67 eV. The observed increase in band gap energy with annealing temperature may be due to the quantum confinement effects. Similarly, refractive index of the films was found to increase with the annealing temperature. The AFM images revealed that films were uniform and pinhole free. The RMS roughness of the films increased from 1.5 nm to 2.5 nm with the increase of annealing temperature. Resistivity of the films decreased linearly with the increase of temperature.
119 citations
TL;DR: In this article, a growth method that allows tailoring of preferred orientation in CuInSe2 thin-films grown on Mo-coated soda-lime glass substrates is presented, and films exhibiting a (204) preferred orientation are demonstrated, in addition to already reported (112) and randomly oriented films.
Abstract: We present a growth method that allows tailoring of preferred orientation in CuInSe2 thin-films grown on Mo-coated soda-lime glass substrates. In particular, films exhibiting a (204) preferred orientation are demonstrated, in addition to already reported (112) and randomly oriented films. Effects of substrate composition, growth temperature, and final film composition on texture phenomena are presented. In general, we find that texture is highly dependent on growth temperature, substrate material and, in the case of Mo-coated soda-lime glass substrates, the structural properties of the Mo layer. We provide evidence for the attainment of such structural orientation, and we present a growth model to explain the mechanism allowing such modifications.
90 citations