MXene‐GaN van der Waals Heterostructures for High‐Speed Self‐Driven Photodetectors and Light‐Emitting Diodes

Abstract Due to their excellent electrical conductivity, high transmittance, and adjustable work function, 2D transition‐metal carbides and nitrides have shown great promise in optoelectronic applications, especially in MXene‐semiconductor devices. In this work, Ti 3 C 2 T X /(n/p)‐GaN van der Waals heterostructures are fabricated and studied. The Ti 3 C 2 T X /(n/p)‐GaN Schottky junctions are confirmed by ultraviolet photoelectron spectroscopy (UPS) with a work function ≈4.2 eV of Ti 3 C 2 T X . Based on the Ti 3 C 2 T X /(n/p)‐GaN Schottky junctions, high‐speed photodetectors and stable orange light emitting diodes (LEDs) are fabricated. The Ti 3 C 2 T X /n‐GaN heterostructure photodetector shows a short rise time (60 ms) and decay time (20 ms), a high responsivity (44.3 mA W −1 ) and on/off ratio (≈11300) under a light source of 365 nm wavelength and 96.9 µW cm −2 power density. And the Ti 3 C 2 T X /p‐GaN heterostructure LED remains a stable orange light emission under bias voltage from 4 to 22 V. The chromaticity coordinates and color temperature of EL spectrum under 22 V are further calculated to be 0.4541, 0.4432, and 2953 K, respectively. The authors believe that this work provides fundamental insight into the applications of MXene in optoelectronic devices.