Layer dependent photo-response of Indium Selenide (InSe) field-effect transistors (FETs)*

Recent interest in optoelectronic properties of 2D materials from group III-VI such as Indium Selenide (InSe) has increased due to their direct band gap in few-layered form. Understanding and optimizing the layer dependent properties of these materials is important for developing future optoelectronics devices. Here we report a detailed investigation of layer dependent (thickness 20 < t < 100 nm) photoconductive behavior of InSe based field-effect transistors (FETs). Our investigations indicate maximum responsivities of ~ 7.84 A/W and ~ 0.59 A/W were obtained for the devices with thickness 20 nm and 100 nm, respectively. We will discuss the correlation between layer thickness and figures of merit such as field effect mobility (μ_FE) and responsivity (R) etc. for the photo-FETs studied.