Emergence of multiple negative differential transconductance from a WSe2 double lateral homojunction platform

Abstract

Recent advances in two-dimensional (2D) van der Waals heterostructures have re-spurred the investigation of non-linear negative differential carrier transport transistors as a potential ingredient for the upcoming digital-driven hyperconnected era. Although notable findings employing various 2D heterojunctions have been recently demonstrated, the performance metrics are insufficient to fulfill requirements for practical device applications, and fundamental difficulties associated with multiple vertical stacking processes in device fabrication must be resolved. Here, we report the realization of multiple negative differential transconductance (NDT) and resistance (NDR) characteristics obtained from a single p-i-n WSe2 double lateral homojunction (DLHJ) transistor. Forming the DLHJ through the selective surface charge transfer doping of a homogeneous bilayer WSe2 film, double NDT characteristics that excel those expected from individual junction components and have high peak-to-valley current ratios (PVCRs) of 36.6 and 12.9 are achieved. Performing combined experimental characterizations and first-principle calculations, obtained exceptional NDT performance at room temperature is determined to originate from the modulation of trap-assisted tunneling and nonlinear 2D band shifts in response to the gate control. Furthermore, the quaternary logic operation based on the triple NDR with the largest PVCR of 137 is achieved by the correlated biasing of the WSe2 DLHJ device.