S. Chaudhuri

Bio: S. Chaudhuri is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Sputter deposition & Nanocrystalline material. The author has an hindex of 5, co-authored 5 publications receiving 71 citations. Previous affiliations of S. Chaudhuri include Haldia Institute of Technology.

Nanostructured ZnTe films prepared by D.C. magnetron sputtering

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.

NANOCRYSTALLINE ZnSe FILMS PREPARED BY HIGH PRESSURE MAGNETRON SPUTTERING

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.

Au/CdS Schottky Diode Fabricated with Nanocrystalline CdS Layer

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.

Electrical conductivity of nanostructured ZnTe films

Abstract: Nanostructured ZnTe films have been deposited by high pressure d.c. magnetron sputtering onto glass substrates. The variation of electrical conductivity with temperature was measured in the temperature range of 100–300 K. The conductivity is found to vary as T − 1 2 within a temperature range 100–150 K, indicating variable range hopping within a Coulomb gap.

Gas Sensing Properties of ZnO Nanowires

Abstract: The review covers up-to-date developments in the growth process of device grade ZnO nanowires, nanobelts and their possible technological applications for the realization of smart gas sensors usable in environmental, automotive, chemical industries and health care fields. The gas sensing mechanism in bulk ZnO as well as in ZnO nanowires and nanobelts for a wide variety of industrial gases like oxygen, hydrogen, carbon monoxide, nitrogen oxide, hydrogen sulphide, ethanol, etc are addressed. In addition, the design aspects, sensitivity and limitations of various types of ZnO nano gas sensors are also discussed.

Theory of the linear and nonlinear optical properties of semiconductor microcrystallites

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.

General Sonochemical Method for the Preparation of Nanophasic Selenides: Synthesis of ZnSe Nanoparticles

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.

Study of electronic defects in CdSe quantum dots and their involvement in quantum dot solar cells.

Abstract: To enhance efficiencies of quantum dot CdSe/TiO2 based solar cells, understanding of the space charge at the CdSe/TiO2 interface is crucial. In this paper, the presence of a shallow acceptor in the CdSe quantum dots is found by means of a detailed impedance and Mott−Schottky (C−2−ϕ) study. Furthermore, it is clearly shown that this acceptor density decreases strongly with increasing quantum dot size. The presence of these defect states may give rise to Auger recombination in small quantum dots and therewith decrease the efficiency of quantum-dot-sensitized solar cells.

Optical properties of nanocrystalline ZnS films prepared by high pressure magnetron sputtering

Abstract: Nanocrystalline ZnS films with different thickness (10–40 nm) were deposited onto quartz and NaCl substrates by magnetron sputtering of a ZnS target in argon plasma. All the films showed a zinc blende structure and the photoluminescence peak positions depended on the surface to volume ratio of the films. The optical absorption in these films could be explained by the combined effects of phonon and inhomogeneity broadening along with optical loss due to light scattering at the nanocrystallites.

The influence of substrate temperature on the morphology, optical and electrical properties of thermal-evaporated ZnSe thin films

Abstract: The structural, morphological, optical and electrical properties of ZnTe films deposited by evaporation were investigated as a function of substrate temperature (at −123 and 27 °C) and post-deposition annealing temperature (at 200, 300 and 400 °C). It was determined that films deposited at both substrate temperatures were polycrystalline in nature with zinc-blende structure and a strong (1 1 1) texture. A small Te peak was detected in XRD spectra for both substrate temperatures, indicating that as-deposited ZnTe films were slightly rich in Te. Larger grains and a tighter grain size distribution were obtained with increased substrate temperature. Scanning electron microscopy (SEM) studies showed that the microstructures of the as-deposited films agreed well with the expectations from structure zone model. Post-deposition annealing induced further grain growth and tightened the grain size distribution. Annealing at 400 °C resulted in randomization in the texture of films deposited at both substrate temperatures. Optical spectroscopy results of the films indicated that the optical band gap value increased from 2.13 to 2.16 eV with increased substrate temperature. Increasing the annealing temperature sharpened the band-edge. Resistivity measurements showed that the resistivity of films deposited at substrate temperatures of −123 and 27 °C were 32 Ω cm, and 1.0 × 104 Ω cm, respectively with corresponding carrier concentrations of 8.9 × 1015 cm−3 and 1.5 × 1014 cm−3. Annealing caused opposite changes in the film resistivity between the samples prepared at substrate temperatures of −123 and 27 °C.