Broadband photocurrent spectroscopy and temperature dependence of band gap of few-layer indium selenide (InSe)

Abstract

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