High-performance deep ultraviolet light detectors composed of MXene/GaN heterostructures enabled by p-type doping of MXenes

Abstract

The performance enhancement of MXene/semiconductor heterostructure-based light detectors is greatly restricted by the relatively small junction barrier due to the limited work function of MXenes. The work function of MXenes can be largely adjusted to approach 600 meV through simple incorporation of V₂O₅ via a charge transfer doping mechanism. Exploiting this strategy, the performance of MXene/GaN heterostructure-based deep ultraviolet (DUV) photodetectors has been greatly improved. Specifically, the photocurrent is enhanced by nearly 3 times, and the dark current is suppressed at the lowest order of magnitude, resulting in improved responsivity and specific detectivity of 121.6 mA/W and 2.23×10¹³ Jones, respectively, at 265 nm. The device also displays an ultralow dark current of 10⁻¹⁴ A, a fast response speed of 0.4 ms/15.1 ms, a large linear dynamic range exceeding 150 dB, and a high DUV/near ultraviolet rejection ratio of 2.41×10⁵. Owing to its good device performance, the detector is capable of sensing weak photon signals produced by a fire flame and functions as an optical receiver to transmit a text signal in a DUV light communication system. The proposed MXene doping method is expected to help develop MXene-based electronic/optoelectronic devices, and the present DUV photodetectors will find potential applications in DUV optoelectronic systems.