Temperature dependent electrical and photoconductive properties of few-layer Indium Selenide (InSe) FETs*

Here we report on the temperature dependent electrical and photoconductive properties of n-type few-layer InSe Field Effect Transistors (FETs), micromechanically exfoliated from bulk crystal grown using chemical vapor transport method. The temperature dependent electrical conduction in these InSe FETs shows two distinct conduction mechanisms. At high temperatures electrical conduction is governed by thermally activated behavior, while at low temperatures electrical conduction follows Mott’s 2D variable range hopping mechanism. Further, photoconductivity measurements show that these InSe FETs display room temperature photo-responsivities of ~ 0.05 AW^-1 when illuminated with a laser of wavelength λ = 658 nm and a power of ~23 nW. The photo-responsivities of these FETs showed several orders of magnitude improvement (up to ~ 15 AW^-1) upon application of a gate voltage (V_G = 60 V). These key findings and temperature dependent photoconductivity study will be presented and discussed.