NISCAIR Online Periodicals Repository Collection: IJPAP Vol.44(02) [February 2006]

I-V measurements of chalcogenide glass thin films

Sun, 29 Jan 2006 22:58:59 GMT

Title: I-V measurements of chalcogenide glass thin films

Authors: Saraswat, Vibhav K; Kishore, Vimal; Saxena, N S; Sharma, T P

Abstract: Measurements of I-V characteristics of Se_85-xTe₁₅Sb_x(where x = 2, 4, 6, 8 and 10) glassy thin films have been carried out at ambient conditions. These measurements have been taken using Keithley Electrometer/High Resistance Meter 6517A in its force voltage measure current (FVMI) mode. Measurements show that the film containing 4 at. wt. % of Sb allows the maximum current to pass through itself as compared to other counterparts of this series. The composition dependence of resistance has been explained on the basis of bond formation between Se and Sb at different compositions and hence Se₈₁Te₁₅Sb₄composition could be termed as “critical composition” in the series under test as it is also strongly supported by dc electrical conductivity, thermal conductivity and thermal diffusivity measurements of these materials in bulk. Besides, the linear relationship between ln (I) and V^1/2 confirm the conduction mechanism as to be Poole-Frenkel type.

Page(s): 196-200

Optical band gap studies on Zn-Te pellets

Sun, 29 Jan 2006 22:58:59 GMT

Title: Optical band gap studies on Zn-Te pellets

Authors: Sharma, R; Saxena, N S; Kumar, S; Sharma, T P

Abstract: Spectroscopic techniques are very useful for characterizing semiconducting and conducting materials. The optical properties (specially reflection spectra) of Zn_xTe_100-x(x=5, 10, 30 and 50) material in pellet form were studied. Polycrystalline semiconducting material has been prepared by Melt quenching method by taking pure Zn and pure Se in appropriate atomic weight ratio. The polycrystalline nature of Zn₅Te₉₅ was confirmed by XRD studies. In order to compare the studies on so prepared polycrystalline material and commercially obtained pure Zn₅₀Te₅₀ material, investigations were carried out on both types of samples. From the analysis of reflection spectra, energy band gaps of Zn_xTe_100-x material have been determined, which were found to increase from 1.67 to 2.31 eV. It is observed that the optical band gap of laboratory prepared Zn₅₀Te₅₀ material is in excellent agreement with that of commercially obtained pure Zn₅₀Te₅₀ material.

Page(s): 192-195

Electro-kinetic wave spectrum in group-IV semiconductors: Effect of streaming carriers

Sun, 29 Jan 2006 22:58:59 GMT

Title: Electro-kinetic wave spectrum in group-IV semiconductors: Effect of streaming carriers

Authors: Ghosh, S; Thakur, Preeti

Abstract: The implanted ions in a group-IV semiconductor agglomerate to form nano-clusters (NCs) and some of them acquire negative charge which change the balance between electron-hole densities in an otherwise compensated semiconductor. An analytical study has been made on wave spectrum of electro-kinetic (EK) waves propagating through such medium. Using multi-fluid analysis and Maxwell’s equations, a linear dispersion relation for the EK wave in such medium has been derived. This dispersion relation is used to study slow electro-kinetic wave phenomena and resultant instabilities numerically. The drift velocities of electrons and holes are found to be responsible for converting two aperiodic modes into periodic ones. They are also found helpful in reducing the absorption of all the four possible EK modes. It is found that choosing the proper values of applied electric field and wave number one may optimize the amplification coefficients of propagating modes.

Page(s): 188-191

Acoustic wave amplification in ion-implanted piezoelectric semiconductor

Sun, 29 Jan 2006 22:58:59 GMT

Title: Acoustic wave amplification in ion-implanted piezoelectric semiconductor

Authors: Ghosh, S; Khare, Pragati

Abstract: An analytical study on excitation of acoustic waves and novel properties introduced by considering that the implanted ions in a group III-V crystal agglomerate to form nanoclusters (NCs) and some of them acquire negative charge in compensated piezoelectric semiconductor plasma has been presented. By using multi-fluid analysis and Maxwell’s equations, a compact dispersion relation for the acoustic wave in a piezoelectric semiconductor has been derived. It is found that the presence of charged NCs not only modifies the wave spectrum but also alters the amplification characteristics even though NCs, on account of their heavy masses, are assumed to be stationary in the background.

Page(s): 183-187