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

The performance of electronic and optoelectronic devices is dominated by charge carrier injection through the metal-semiconductor contacts. Therefore, creating low-resistance electrical contacts is one of the most critical challenges in the development of devices based on new materials, particularly in the case of two-dimensional semiconductors. Herein, we report a strategy to reduce the contact resistance of MoS2 via local pressurization. We fabricated electrical contacts using an atomic force microscopy tip and applied variable pressure ranging from 0 to 25 GPa. By measuring the transverse electronic transport properties, we show that MoS2 undergoes a reversible semiconducting-metallic transition under pressure. Planar devices in field effect configuration with electrical contacts performed at pressures above similar to 15 GPa show up to 30-fold reduced contact resistance and 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 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 for exploring emergent phenomena under mechano-electric modulation.