Schottky-barrier thin-film transistors based on HfO2-capped InSe

Indium selenide (InSe) is an emerging two-dimensional semiconductor and a promising candidate for next generation thin film transistors (TFTs). Here, we report on Schottky barrier TFTs (SB-TFTs) in which a 0.9-nm-thick HfO2 dielectric layer encapsulates an InSe nanosheet, thus protecting the InSe-channel from the environment and reducing the Schottky-contact resistance through a dielectric dipole effect. These devices exhibit a low saturation source-drain voltage Vsat < 2 V and current densities of up to J = 2 mA/mm, well suited for low-power electronics. We present a detailed analysis of this type of transistor using the Y-function method from which we obtain accurate estimates of the contact resistance and field-effect mobility.