MXene–Silicon Van Der Waals Heterostructures for High‐Speed Self‐Driven Photodetectors

MXenes, or transition metal carbides or nitrides, as an advanced 2D materials have already attracted extensive attention due to their high conductivity and large specific surface area for applications in the field of energy storage. MXenes also have many other advanced properties such as good transmittance and adjustable work function over a large range. However, few works study the properties of MXenes in the field of optoelectronics. Here, the optoelectronic properties of Ti3C2TX (with a work function of 4.37 eV) on n‐type silicon (n‐Si) of vertical van der Waals heterostructures are studied. The Ti3C2TX not only functions as the transparent electrode but also contributes to the separation and transport of photo‐induced carriers. After investigations on the influence of annealing, temperature, illumination, and applied voltage on the performance of Ti3C2TX/n‐Si Schottky junction heterostructures, this study fabricates a self‐driven vertical junction photodetectors with high response and recovery speeds. It is believed that the excellent photoelectric properties of MXenes will attract many researchers' attention to the application of MXenes in the photoelectrical field. Ti3C2TX/n‐Si van der Waals heterostructures are fabricated by dropping Ti3C2TX colloidal solution on n‐Si substrate. The Ti3C2TX film not only functions as the transparent electrode but also contributes to the separation and transport of photo‐induced carriers. On/off ratio and responsivity of the optimized Ti3C2TX/n‐Si device can reach to ≈105 and 26.95 mA W−1, respectively.