Unipolar P‑Type Electrical Conduction and Improved Photodetection of MoTe<sub>2</sub> Transistors with Unique SnSe<sub>2</sub> Contacts

Although two-dimensional transition metal dichalcogenides\n(TMDCs) exhibit excellent electrical and optical properties, the Schottky\nbarrier at the contact electrode/TMDC interface imposes severe limitations\non device performance. Herein, we demonstrate that the quasi-Ohmic\ncontact characteristics with an ignorable Schottky barrier of 13.1\nmeV can be achieved in MoTe<sub>2</sub> transistors by using the degenerated\nsemiconductor SnSe<sub>2</sub> as the contact electrodes. The SnSe<sub>2</sub>-contacted MoTe<sub>2</sub> transistors present unipolar p-type\nconduction with an on/off current ratio of over 10<sup>5</sup>. Furthermore,\nthe SnSe<sub>2</sub>-contacted MoTe<sub>2</sub> transistor exhibits\nexcellent photodetection performance, with an outstanding photoresponsivity\nof 616.7 A/W, a high specific detectivity of 5.02 × 10<sup>12</sup> Jones, an ultrafast response speed of 40 ns, and a 3 dB bandwidth\nof 47 MHz. This study provides a feasible strategy for achieving both\nrare unipolar p-type MoTe<sub>2</sub> transistors and high-performance\nphototransistors, which is expected to have a significant impact on\nthe engineering of future two-dimensional electronic and optoelectronic\ndevices.