Two-Dimensional Field-Effect Transistors Based on Lateral Heterojunctions of Transition Metal Dichalcogenides: Dissipative Quantum Transport Modeling

Reducing the contact resistance of field-effect transistors (FETs) based on 2-D materials is one of the key improvements required to enable the integration of such transistors in an advanced semiconductor manufacturing process. Suitably designed lateral heterojunctions provide an opportunity to independently tailor the contact and channel properties to optimize contact resistance. Inspired by the recent experimental demonstration of a 2-D p-type Schottky barrier, here we use quantum transport simulations to estimate the performance of p-type transistors in which the channel consists of a lateral heterostructure of NbS2/MoS2/NbS2 (semimetal-semiconductor–semimetal). We find that the gate alignment with the channel is a critical design parameter, strongly influencing the capability of the gate to modulate the Schottky barrier at the MoS2/NbS2 interface. This effect is also found to significantly affect the scaling behavior of the device.

I. Introduction

The possibility to use 2-D materials in an industrial complementary metal-oxide semiconductor (CMOS) process depends on several factors, but few are as critical as the capability to fabricate low-resistance metal contacts. Unfortunately, 2-D semiconductors tend to form high Schottky barriers with bulk metals, and the difficulty in achieving high doping levels in monolayers hinders the adoption of the conventional approach based on thinning these barriers enough to make them transparent to carrier tunneling [1], [2], [3].