Low resistance electrical contacts to few-layered MoS₂ by local pressurization

Abstract

The performance of electronic and optoelectronic devices is dominated by charge carrier injection through metal–semiconductor contacts. Therefore, creating low-resistance electrical contacts is one of the most critical challenges to the development of devices based on new materials, especially in the case of two-dimensional semiconductors. Here, we report a strategy to reduce contact resistance to MoS2 via local pressurization. We make electrical contacts using an Atomic Force Microscopy tip and apply variable pressure ranging from 0 to 25 GPa. By measuring transverse electronic transport properties, we show that MoS2 under pressure undergoes a reversible semiconducting-metallic transition. Planar devices in field effect configuration with electrical contacts performed at pressures above ~15 GPa show an up to 30-fold reduced contact resistance and an up to 25-fold improved field-effect mobility when compared to those measured at low pressure. Theoretical simulations show that this enhanced performance is due to an improved charge injection to the MoS2 semiconductor channel through the metallic MoS2 phase obtained by pressurization. Our results suggest a novel strategy for realizing improved contacts to MoS2 devices by local pressurization and to explore emergent phenomena under mechano-electric modulation.

Schottky barrier reduction on optoelectronic responses in heavy ion irradiated WSe2 memtransistors

“…Usually, high Schottky barriers at the metal-semiconductor interfaces can seriously limit the improvement of monolayer 2D semiconductor FETs. A series of strategies have been reported to reduce the height of the Schottky barrier to obtain high-performance monolayer 2D semiconductor FETs, [51][52][53] whereas the reduction of contact resistance or Schottky barrier height would reduce the potential well for optoelectronic memory. This study showed that the defects at the metal-semiconductor interface caused by heavy ion irradiation were an effective way to improve the contact resistance and reduce the Schottky barrier.…”

Light‐Induced Ferroelectric Modulation of p‐n Homojunctions in Monolayer MoS2

“…This ensures a good electrical contact between the probes and the MoS 2 . [ 54 ] The experimental set up includes a Keithley 2400 source meter to apply the bias voltage between electrodes, a Femto DLPCA‐200 variable‐gain low‐noise current preamplifier, and a Keithley 2000 multimeter to measure the output of the preamplifier.…”