Exceptional ballisticity in monolayer BX (X = P, As, Sb) transistors

Abstract

The initial excitement surrounding the potential use of two-dimensional (2D) semiconductors as a replacement for bulk silicon in ultra-thin body transistors has somewhat diminished due to their inferior room temperature mobility. Such phenomenon appears to be universal since it stems from the intrinsically high “density of scattering.” Here, we investigate three boron compounds, BP, BAs, and BSb, which show the potential to disrupt this universality due to their low effective masses and high optical phonon energies. Our investigation starts with the ab initio calculation of an inter- and an intravalley electron–phonon coupling matrix and the associated deformation potentials, which are then used to develop dissipative quantum transport models. We then calculate room temperature mobilities for electrons and holes using those models and find them superior to those of bulk silicon. We finally report the drain current characteristics of monolayer BX-based n- and p-type transistors, observing near-coherent transport and exceptional ballisticity (75%–87%) along with high drain current (1400–1900μAμm−1) in 25 nm channel length devices. Considering the various technological challenges associated with 2D transistor downscaling, BX may pave the way for realizing high-frequency integrated circuits based on 2D semiconductors.