Papers by Author: G. Mohan Rao

Abstract: Abstract: Alumina (Al2O3) thin films were deposited over glass and Si substrates by DC reactive magnetron sputtering at an oxygen partial pressure of 0.03 Pa. The presence of aluminium and oxygen was confirmed using x-ray photoelectron spectroscopy and the films were found to be nearly stoichiometric or oxygen rich at a sputtering power of 70 W and 60 W, respectively. The as-deposited films were found to be amorphous. Subsequent annealing experiments in vacuum revealed that crystallisation started at 550oC and increased thereafter at higher annealing temperatures for those films deposited at a sputtering power of 70 W. The topography of the as-deposited and annealed films was analyzed by Atomic force microscopy and a progressive increase in the rms roughness of the films was observed with increase in the annealing temperature and the results are discussed

Abstract: This work describes the electrical switching behavior of three telluride based amorphous chalcogenide thin film samples, Al-Te, Ge-Se-Te and Ge-Te-Si. These amorphous thin films are made using bulk glassy ingots, prepared by conventional melt quenching technique, using flash evaporation technique; while Al-Te sample has been coated in coplanar electrode geometry, Ge-Se-Te and Ge-Te-Si samples have been deposited with sandwich electrodes. It is observed that all the three samples studied, exhibit memory switching behavior in thin film form, with Ge-Te-Si sample exhibiting a faster switching characteristic. The difference seen in the switching voltages of the three samples studied has been understood on the basis of difference in device geometry and thickness. Scanning electron microscopic image of switched region of a representative Ge15Te81Si4 sample shows a structural change and formation of crystallites in the electrode region, which is responsible for making a conducting channel between the two electrodes during switching.