Investigation of Temperature Dependent Optical Modes in GexAs35-xSe65 Thin Films: Structure Specific Raman, FIR and Optical Absorption Spectroscopy

TL;DR

This study investigates how temperature and composition affect the optical modes and structure of GexAs35-xSe65 thin films using Raman, FIR, and absorption spectroscopy, revealing structural units and their optical properties.

Contribution

It provides new insights into the temperature and composition dependence of structural units and optical properties in GexAs35-xSe65 thin films, including formation of Se8 rings.

Findings

Identification of GeSe4/2 and AsSe3/2 units and their linear scaling with temperature and composition.

Observation of Se8 ring formation at lower temperatures.

Optically tunable absorption spectra related to structural changes.

Abstract

In this article, we present a comprehensive study of temperature and composition dependent Raman spectroscopy of GexAs35-xSe65 thin films to understand different structural units responsible for optical properties. Strikingly, our experimental results uncover the ratio of GeSe4/2 tetrahedral and AsSe3/2 pyramidal units in GexAs35-xSe65 thin films and their linear scaling relationship with temperature and x. An important notable outcome of our study is the formation of Se8 rings at lower temperatures. Our experimental results further provide interesting optical features, thermally and compositionally tunable optical absorption spectra. Detailed structure specific FIR data at room temperature also present direct information on the structural units in consistent with Raman data. We foresee that our studies are useful in determining the lightinduced response of these films and also for their potential applications in optics and optoelectronics.