Remote modulation doping in van der Waals heterostructure transistors

Abstract

Carriers in a molybdenum disulfide transistor can be modulated without decreasing mobility by remote doping and charge transfer through a van der Waals heterostructure, which avoids dopant-induced impurity scattering in the channel. Doping is required to modulate the electrical properties of semiconductors but introduces impurities that lead to Coulomb scattering, which hampers charge transport. Such scattering is a particular issue in two-dimensional semiconductors because charged impurities are in close proximity to the atomically thin channel. Here we report the remote modulation doping of a two-dimensional transistor that consists of a band-modulated tungsten diselenide/hexagonal boron nitride/molybdenum disulfide heterostructure. The underlying molybdenum disulfide channel is remotely doped via controlled charge transfer from dopants on the tungsten diselenide surface. The modulation-doped device exhibits two-dimensional-confined charge transport and the suppression of impurity scattering, shown by increasing mobility with decreasing temperature. Our molybdenum disulfide modulation-doped field-effect transistors exhibit a room-temperature mobility of 60 cm(2) V-1 s(-)(1); in comparison, transistors that have been directly doped exhibit a mobility of 35 cm(2) V-1 s(-)(1).