High Electron Mobility and Saturation Velocity in Indium Deposited InSe Transistor

Abstract

The realization of a high-frequency electron system demands a high saturation velocity with an understanding of high-field electron transport properties. This thesis reports high-field electron transport characteristics in 2D indium selenide (InSe). In our devices, multilayer InSe is on a hexagonal boron nitride substrate and encapsulated by indium, achieving an outstanding electron mobility of ~2700 cm^2/Vs at room temperature. Using the four-terminal methodology, we measure a drift velocity in the InSe as a function of the external electric field and further discuss the impact of temperature and carrier density. Extracted saturation velocity reaches ~2.3 × 10^7 cm/s at room temperature, which is superior to those of other gapped 2D semiconductors. Employing the optical phonon emission model modified for a parabolic dispersion, optical phonon energy of InSe is estimated as ~16±5 meV, which is close to the theoretical optical phonon branch of InSe. Our comprehensive study of high-field transport of InSe suggests the potential application of InSe in ultrahigh radio frequency transistors.