Performance improvement in p-Type WS2 field-effect transistors with 1T phase contacts

The non-ideal contact between the metal electrode and semiconducting channel has become one of the major bottlenecks degrading the performance of field-effect transistors (FETs) based on two-dimensional (2D) materials. The formation of the Schottky barrier prohibiting the carrier injection as well as the Fermi level pinning effect have a strong impact on the device performance. In this work, we fabricated a 2D WS2 FET device with engineered metallic 1T phase at the source/drain region by using Li intercalation method. As compared to the device with conventional 2H-WS2 channel, the engineered FET with a 2H-WS2/1T-WS2 junction has exhibited greatly improved performance such as over 10 times higher carrier mobility and steeper subthreshold slope. Such results have demonstrated the boosted carrier injection into the channel over the engineered metal contact as well as the reduced tunnel barrier width between the 2H/1T-WS2 junction. This can be attractive for the large-scale integration of the 2D devices towards high-performance and high-reproducibility nanoelectronics applications.