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

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, Ti₃C₂T_X/(n/p)-GaN van der Waals heterostructures are fabricated and studied. The Ti₃C₂T_X/(n/p)-GaN Schottky junctions are confirmed by ultraviolet photoelectron spectroscopy (UPS) with a work function ≈4.2 eV of Ti₃C₂T_X. Based on the Ti₃C₂T_X/(n/p)-GaN Schottky junctions, high-speed photodetectors and stable orange light emitting diodes (LEDs) are fabricated. The Ti₃C₂T_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 Ti₃C₂T_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.