Ballistic Transport in Monolayer Black Phosphorus Transistors

We report a comprehensive theoretical investigation of ballistic quantum transport in monolayer black phosphorus (ML-BP) field-effect transistors (FETs). Our calculation is from tight binding atomistic model based on the nonequilibrium Green´s function formalism. Several important device properties, including the drain current, ON-OFF ratio, transfer characteristic, short channel effects, intrinsic delay, and power delay product are determined against the channel length, transport direction, bias, and gate voltages. The atomistic simulation provides microscopic understanding of the device physics. Due to the anisotropic band structure of ML-BP, an orientation-dependent transport characteristic manifests itself in the major transistor properties. Comparing device performance in the zigzag and armchair direction (AD), we predict that transport along the AD has higher ON-state current and faster switching speed due to the lighter carrier effective mass. Comparing with ML MoS₂ FET, ML-BP FET produces higher current density and faster switching speed, but costs more switching energy. Double gated ML-BP FETs show promising device characteristics that fulfill the international technology roadmap for semiconductors requirements in the 10-year horizon.