MXene‐Germanium Schottky Heterostructures for Ultrafast Broadband Self‐Driven Photodetectors

Abstract A novel 2D layered material Ti 3 C 2 T x (MXene) is favored by researchers in the application field of optoelectronics due to its tunable work function, great light transmittance, and excellent electrical conductivity. In this work, Ti 3 C 2 T x /n‐germanium (MXene/n‐Ge) Schottky heterostructures are fabricated and investigated. Schottky contacts of MXene with n‐Ge are identified by ultraviolet photoelectron spectroscopy (UPS). Based on the MXene/n‐Ge Schottky junctions, an ultrafast, broadband, and self‐powered photodetector is demonstrated and studied. The MXene/n‐Ge device exhibits excellent photoresponse from ultraviolet to near‐infrared light illumination. In particular, it shows an excellent on/off ratio (≈10 4 ), a high responsivity (3.14 A/W), a larger specific detectivity (2.14 × 10 11 Jones), and an ultrafast response speed (t rise of 1.4 µs and t decay of 4.1 µs). Moreover, the MXene/n‐Ge Schottky heterostructure photodetector also shows excellent low‐temperature work characteristics of 73 K. It is believed that this work will attract more researchers’ attention to MXene in the field of optoelectronic devices.