Low Temperature Electronic Transport in Field-effect Transistors based on 2D Layers of Copper Indium Selenide (CuIn₇Se₁₁)

Ternary system of Copper Indium Selenide (CIS) in thin film form has been extensively used in optoelectronics industry in the past due to its exceptional optical properties. It is, therefore, expected that 2D layers of CIS could play a key role for developing next generation micro/nanoscale optoelectronics devices based on 2D materials. We will report on the fabrication of field-effect transistors (FETs) using few-layers of CuIn₇Se₁₁ flakes exfoliated from crystals grown using chemical vapor transport technique. Our transport measurements indicate n-type FET with electron field effect mobility, µ_FE ≈ 27 cm² V^-1 s^-1 at room temperature when silicon dioxide (SiO₂) is used as a back gate. Low temperature electronic transport measurements, in order to understand the nature of electron transport, performed on these devices will also be presented. Our results suggests the possibility of two-dimensional (2D) variable range hopping (VRH) mechanism in CuIn₇Se₁₁ FETs. Temperature dependence of several other key parameters associated with FETs such as field effect mobility, threshold voltage, subthreshold swing, interface trap density, Schottky barrier height etc. will presented and discussed.