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

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.