Ashwani Sharma

Frequency-dependent electrical conductivity of bismuth-modified amorphous semiconductors (GeSe3.5)100−xBix☆

Abstract An investigation of the AC conductivity and dielectric relaxation of Bi-modified amorphous germanium selenide semiconductors (Ge Se 3.5 ) 100− x Bi x in the frequency range 100 Hz–10 KHz and in the temperature span 180 K–440 K has been undertaken for the first time. The AC conductivity is found to be proportional to ω s . The temperature dependence of σ AC ( ω ) and the parameter s in all the compositions is reasonably interpreted by the correlated barrier hopping model (CBH). The analyis of the results reveals that the electronic conduction in x = 0, 2, 4 compositions takes place via bipolaron hopping. Addition of Bi in higher concentration ( x = 10) induces a new type of microscopic environment and new defects which take part in the single polaron hopping conduction process.

On the glass formation tendency in (PbS)x·(M2S3)1−x (M = As, Sb)

Abstract Materials in the system (PbS)x·(M2S3)1−x (M = As, Sb, Bi) form alloy compounds over a wide range of compositions. PbAsS forms glasses upto x = 0.625, PbSbS produces glassy compounds only near eutectic composition and PbBiS only forms crystalline compounds using the conventional liquid quenching technique. The vitrification characteristics of this series of solids is investigated using the basic crystal chemistry of the two participating systems: PbS and M2S3. Further, disorder induced defects in PbAsS glasses, are studied using the long term relaxation of photoconductivity.

Steady state and transient photoconductivity in a-Sb15Ge10Se75

Abstract An investigation of photoconductivity in thin films of Sb 15 Ge 10 Se 75 prepared by vacuum evaporation is reported. The measurements were carried out at various temperatures and illumination intensities. Photoconductivity is found to increase exponentially with no maxima found in temperature range (303–373 K). The value of I ph / I d is found to decrease with an increase in temperature. In order to investigate the nature of decay following steady state illumination, transient photoconductivity measurements have also been carried out at various temperatures and illumination intensities. The results are well explained by the dispersive diffusion controlled recombination of excess D° states in localised-localised recombination.

Influences of Dopant Concentration on Crystallography, Optical and Electrical Properties of Cadmium Oxide Nanoparticles

Influences of Dopant Concentration on Crystallography, Optical and Electrical Properties of Cadmium Oxide Nanoparticles Cadmium oxide (CdO) nanoparticles doped with different amount of rare earth metal Neodymium (Nd) ions have been prepared by Chemical co precipitation method. The doping level was varied from [Nd/Cd] = 0.1 to 10 wt%. Crystallography analysis of these materials is carried out by X- ray diffraction (XRD) which reveals that average crystalline size is in nano region i.e. 30-30.8 nm. The synthesized nanomaterial was characterized by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transformation infrared spectroscopy (FTIR), UV-Visible Spectroscopy (UV-Vis). Electrical properties were also studied as a function of dopant concentration. Present studies also investigate the effect of varying dopant concentration on morphology and topography of as prepared nanomaterial.