Origin of giant photocontraction in obliquely deposited amorphous Ge_xSe_{1-x} thin- films and the intermediate phase

TL;DR

This study investigates the origin of giant photocontraction in obliquely deposited amorphous Ge_xSe_{1-x} thin-films, revealing the role of the intermediate phase and structural features through various spectroscopic and microscopic analyses.

Contribution

It introduces a detailed analysis of how oblique deposition and the intermediate phase influence photocontraction in Ge-Se thin films, a novel insight into their structural and optical properties.

Findings

Giant photocontraction occurs in obliquely deposited Ge-Se films.

The intermediate phase plays a key role in photocontraction.

Structural columnar features are confirmed by SEM.

Abstract

Obliquely deposited amorphous Ge_xSe{1-x} thin-films at several compositions in the 0.15 < x < 0.333 range, and at several obliqueness angles in the 0 < alpha < 80 range at each x were evaporated on Si and glass substrates. Here alpha designates the angle between film normal and direction of vapor transport. Raman scattering, ir reflectance and optical absorption measurements were undertaken to characterize the vibrational density of states and optical band gaps. Edge views of films in SEM confirm the columnar structure of obliquely (alpha = 80) deposited films. Films, mounted in a cold stage flushed with N2 gas, were irradiated to UV radiation from a Hg-Xe arc lamp, and