Size Effect Influence on the Electronic Properties of Ge_2Sb_2Te_5 Films Prepared by Ion Plasma Sputtering

摘要

Physical and chemical criteria for ion plasma deposition of chalcogenide glass nano-films have been studied. Research results demonstrate structure, temperature dependences and electrical conductivity data of nanoscaled Ge_2Sb_2Te_5 films. Thin films were obtained by ion-plasma sputtering with thickness from 25 to 175 nm. Scanning and Transmission Electron Microscopy images revealed amorphous and homogeneous film structure. Temperature dependence of films electrical conductivity investigation was performed. It has been shown that with decreasing film thickness the conductivity decreases and the activation energy of conductivity increases. It has been found from studies of the current-voltage Ge_2Sb_2Te_5 film characteristics reversible switching effect caused by a reversible phase transformation "amorphous <->polycristalline state" takes place. The threshold voltage U_(th) and switching time t_(sw) with decreasing film thickness were reduced significantly.