Polarity-dependent twist-controlled resonant tunneling device based on few-layer WSe2

Abstract

Few-layer (FL) transition metal dichalcogenides have been found to exhibit discrete subbands, called van der Waals quantum well (vdWQW) states, resulting from out-of-plane quantum confinement. In this study, we reveal the twisted-resonant tunneling characteristics of a vdWQW device using a three-layer (3L) WSe2/h-BN/3L-WSe2 junction with different twist angles θtunnel between the two 3L WSe2 flakes. Using an ambipolar graphene contact to WSe2, two primary vdWQW states of 3L WSe2 located in the conduction band (CB) and valence band (VB) were investigated. We found that while the current peak positions due to the electron resonant tunneling between the CB-QW states significantly change with θtunnel having a periodicity of 60, the hole resonant tunneling between the VB-QW states exhibits no θtunnel dependence; these are due to different angular dispersions of two vdWQWs. The results highlight the different twistronic properties of CB and VB vdWQWs in FL WSe2.