Physics of electron emission and injection in two-dimensional materials: Theory and simulation

Electrically contacting two-dimensional (2D) materials is an inevitable process in the fabrication of devices for both the study of fundamental nanoscale charge transport physics and the design of high-performance novel electronic and optoelectronic devices. The physics of electrical contact formation and interfacial charge injection critically underlies the performance, energy-efficiency and the functionality of 2D-material-based devices, thus representing one of the key factors in determining whether 2D materials can be successfully implemented as a new material basis for the development of next-generation beyond-silicon solid-state device technology. In this review, the recent developments in the theory and the computational simulation of electron emission, interfacial charge injection and electrical contact formation in 2D material interfaces, heterostructures, and devices are reviewed. Focusing on thermionic charge injection phenomena which are omnipresent in 2D-materials-based metal/semiconductor Schottky contacts, we summarize various transport models and scaling laws recently developed for 2D materials. Recent progress on the first-principle density functional theory simulation of 2D-material-based electrical contacts are also reviewed. This review aims to provide a crystalized summary on the physics of charge injection in the 2D Flatlands for bridging the theoretical and the experimental research communities of 2D material device physics and technology.