Photon, electron and ion beam induced physical and optical densification in chalcogenide films

Abstract

Irradiation of 80° deposited Se-Ge films with band gap photons, 8 keV electrons and 50 keV He⁺ ions produces, primarily irreversible red shift of the absorption edge and major changes in doping and electrochemical adsorption processes. These changes have been attributed predominantly to the radiation-induced thickness and hence volume contraction resulting due to the physical collapse of the low density columnar microstructure of the obliquely deposited films. The farir and Urbach tail studies reveal an enhanced strength of electron-phonon coupling, in obliquely deposited films having a very porous columnar microstructure, compared to normally deposited films. It has been shown that this enhanced electron phonon coupling is conducive to large thickness contraction and associated changes. These changes have been used in reprographic and lithographic applications. A correlation has been established between the thickness contraction and lithographic parameters. The possibility of generating both positive and negative relief patterns on the same film by controlling the etching time has been demonstrated.