Unipolar P-Type Electrical Conduction and Improved Photodetection of MoTe₂ Transistors with Unique SnSe₂ Contacts

Although two-dimensional transition metal dichalcogenides (TMDCs) exhibit excellent electrical and optical properties, the Schottky barrier at the contact electrode/TMDC interface imposes severe limitations on device performance. Herein, we demonstrate that the quasi-Ohmic contact characteristics with an ignorable Schottky barrier of 13.1 meV can be achieved in MoTe2 transistors by using the degenerated semiconductor SnSe2 as the contact electrodes. The SnSe2-contacted MoTe2 transistors present unipolar p-type conduction with an on/off current ratio of over 105. Furthermore, the SnSe2-contacted MoTe2 transistor exhibits excellent photodetection performance, with an outstanding photoresponsivity of 616.7 A/W, a high specific detectivity of 5.02 × 1012 Jones, an ultrafast response speed of 40 ns, and a 3 dB bandwidth of 47 MHz. This study provides a feasible strategy for achieving both rare unipolar p-type MoTe2 transistors and high-performance phototransistors, which is expected to have a significant impact on the engineering of future two-dimensional electronic and optoelectronic devices.