Broadband Photocurrent Spectroscopy and Temperature Dependence of Band-gap of Few-Layer Indium Selenide

TL;DR

This study investigates the temperature-dependent band-gap of few-layer Indium Selenide using photocurrent spectroscopy, revealing a slight increase in band-gap at lower temperatures and estimating Debye temperatures through theoretical models.

Contribution

It provides the first detailed temperature-dependent band-gap measurements of few-layer InSe and compares experimental results with theoretical models to estimate Debye temperatures.

Findings

Room temperature E_g ~ 1.254 eV

E_g increases to ~1.275 eV at low T

Debye temperatures estimated from models

Abstract

Understanding broadband photoconductive behaviour in two dimensional layered materials are important in order to utilize them for a variety of opto-electronic applications. Here we present our results of photocurrent spectroscopy measurements performed on few layer Indium Selenide (InSe) flakes. Temperature (T) dependent (40 K < T < 300 K) photocurrent spectroscopy was performed in order to estimate the band-gap energies E_g(T) of InSe at various temperatures. Our measurements indicate that room temperature E_g value for InSe flake was ~ 1.254 eV, which increased to a value of ~ 1.275 eV at low temperatures. The estimation of Debye temperatures by analysing the observed experimental variation of E_g as a function of T using several theoretical models is presented and discussed.