Few-layer phosphorene: An ideal 2D material for tunnel transistors

Abstract

2D transition metal dichalcogenides (TMDs) have attracted a lot of attention recently for energy-efficient tunneling-field-effect transistor (TFET) applications due to their excellent gate control resulting from their atomically thin dimensions. However, most TMDs have bandgaps (E g) and effective masses (m ∗) outside the optimum range needed for high performance. It is shown here that the newly discovered 2D material, few-layer phosphorene, has several properties ideally suited for TFET applications: 1) direct E g in the optimum range ∼1.0-0.4 eV, 2) light transport m ∗ (0.15 m 0), 3) anisotropic m ∗ which increases the density of states near the band edges, and 4) a high mobility. These properties combine to provide phosphorene TFET outstanding I ON ∼ 1 mA/um, ON/OFF ratio ∼ 10 6 for a 15 nm channel and 0.5 V supply voltage, thereby significantly outperforming the best TMD-TFETs and CMOS in many aspects such as ON/OFF current ratio and energy-delay products. Furthermore, phosphorene TFETS can scale down to 6 nm channel length and 0.2 V supply voltage within acceptable range in deterioration of the performance metrics. Full-band atomistic quantum transport simulations establish phosphorene TFETs as serious candidates for energy-efficient and scalable replacements of MOSFETs.