Intrinsic Electronic Properties of BN Encapsulated, van der Waals Contacted MoSe$_2$ FETs

TL;DR

This study investigates the intrinsic electronic transport properties of ultraclean, encapsulated MoSe2 FETs with van der Waals gold contacts, revealing high mobility, low trap density, and excellent device performance at room temperature.

Contribution

It provides new insights into the physics of van der Waals contacts and encapsulation effects on 2D MoSe2 FETs, demonstrating improved device characteristics.

Findings

Low interfacial trap density ($10^{10}\,cm^{-2}$)

High carrier mobility ($68\,cm^{2} extperiodcentered V^{-1} extperiodcentered s^{-1}$)

Subthreshold swing below 65 mV/dec

Abstract

Two-dimensional (2D) semiconductors have attracted considerable interest for their unique physical properties. Here, we report the intrinsic cryogenic electronic transport properties in few-layer MoSe$_2$ field-effect transistors (FETs) that are simultaneously van der Waals contacted with gold electrodes and are fully encapsulated in ultraclean hexagonal boron nitride dielectrics. The FETs exhibit electronically favorable channel/dielectric interfaces with low densities of interfacial traps ($10^{10}\,$cm$^{-2}$), which lead to outstanding device characteristics at room temperature, including a near-Boltzmann-limit subthreshold swings ($\lt65\,$mV/dec), a high carrier mobility ($68\,$cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$), and a negligible scanning hysteresis ($\lt15\,$mV). The dependence of various contact-related quantities on temperature and carrier density are also systematically characterized to understand the van der Waals contacts between gold and MoSe$_2$. The results provide insightful information on the device physics in van der Waals contacted and encapsulated 2D FETs.