Performance limits projection of black phosphorous field-effect transistors

TL;DR

This paper analyzes the theoretical performance limits of monolayer black phosphorous FETs, highlighting their anisotropic properties and superior ballistic performance compared to MoS2 and Si FETs.

Contribution

It provides a projection of the ultimate performance limits of BP FETs considering ballistic transport and anisotropic effective masses.

Findings

BP FETs have higher drive current in the armchair direction.

Intrinsic delay is around 50 fs for 20 nm BP FETs.

BP FETs outperform MoS2 and Si FETs in ballistic limits.

Abstract

Ballistic device performance of monolayer black phosphorous (BP) field-effect transistors (FET) is investigated in this work. Due to the anisotropic effect mass of the carriers, the ON-state current is dependent on the transport direction. The effective masses are lower in the "armchair" direction which provides higher drive current at the same biasing. The degree of anisotropy is higher for the holes, which improves the performance of p-type devices. The intrinsic delay of 20 nm BP FETs is in the range of 50 fs at ON-/OFF-current ratio of 4 orders. Monolayer BP FETs outperform both MoS$_2$ and Si FETs for both n- and p-type devices in terms of ballistic performance limits, due to highly anisotropic band structure.