Nanolayered Graphene/Hexagonal Boron Nitride/n-AlGaN Heterostructures as Solar-Blind Deep-Ultraviolet Photodetectors

The spectral specificity of deep-ultraviolet (UV) photodetectors makes them useful in many fields, spanning from disinfection of various surfaces and water purification to optical communication. As silicon-based devices show obvious disadvantages as UV devices because of their low band gap, semiconductor materials with a wide band gap exceeding 4 eV serve as excellent alternatives. In this paper, by the integration of the unique properties of each constituent material, we design a nanolayered graphene/insulator/semiconductor (graphene/hBN/n-AlGaN) deep-UV photodetector with high performance. The wide-band gap AlGaN semiconductor enables the detection of deep-UV signals without the requirement of a UV-pass filter and thus acts as a true solar-blind photodetector. In addition, the several nanolayered graphene-hBN heterostructure is utilized to enhance the performance of photodetectors, which successfully solves the strain issue between graphene and the conventional bulk insulators. Besides, the high transparency of graphene can enable incident light to directly excite the active layer with negligible optical loss, and the two-dimensional hBN insulator is beneficial to reduce dark current and assist the quantum tunneling of photogenerated carriers. Interestingly, the photodetectors demonstrated in this work show the highest responsivity and detectivity compared with previously reported AlGaN-based deep-UV photodetectors.