Bound Charge Engineering: A Novel Approach to Strengthen Screening in Low-Dimensional Systems

Low-dimensional materials, e.g. 2D semiconductors and nanowires (NWs), have garnered great interest owing to their prospects for nanoelectronics. However, these systems have fewer free charges than 3D counterparts, resulting in weak electrostatic screening. This leads to long depletion lengths at junctions, severe limits on device downscaling, and impairs operation of such systems as tunnel field-effect transistors (TFETs). Chemical doping is typically used to add free charges but compromises material and electrical properties at high concentrations. To resolve this problem, we introduce the idea of bound charge engineering (BCE), a novel approach of engineering surface bound charges to strengthen screening. Established by basic electrostatics, BCE is broadly applicable to low-dimensional systems. Through atomistic quantum transport simulations, we show that BCE greatly increases the on-off ratio and on-state current of silicon NW TFETs and may thereby pave a path toward improved low-power nanotransistors [1].

[1] R. J. Prentki et al., “Nanowire transistors with bound charge engineering”, To appear in Phys. Rev. Lett. (2020).