Contact Resistance Reduction of WS2 FETs Using High-Pressure Hydrogen Annealing

The transition metal dichalcogenides (TMDCs) have been extensively investigated for various applications such as logic, memory and optical devices, and sensors. The pressing challenge in the research of TMDCs is the electrical performance limited by the high contact resistance. We report more than 5000 times reduction in the contact resistance of WS2 field-effect transistor (FET) with Ti contact (81 MΩ μm to 14.6 kΩ μm) by high-pressure hydrogen annealing. Schottky barrier height reduction appears to play a major role in the reduction of the contact resistance. This process can be used to reduce the contact resistance even further by combining with a doping technique for TMDCs and a contact metal optimization for TMDC FETs.