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.

Random lasers exhibit many exotic properties, including chaotic behavior, light localization, broad angular emission, and cost-effective fabrication, which enable them to attract both scientific and industrial interests. However, before the realization of their potential applications, several challenges still remain including the underlying mechanism and controllability due to their inherent multidirectional and chaotic fluctuations. Through more than two decades of collaborative efforts, the discovery of Anderson localization in random lasers provides a plausible route to resolve the difficulties, which enables one to tailor the number of lasing modes and stabilize the emission spectra. However, the related studies are rather rare and only restricted to limited wavelengths. In this study, based on enhanced Anderson localization assisted by surface plasmon resonance, spectrally stable deepultraviolet lasing action in AlGaN multiple quantum wells (MQWs) is demonstrated. Our work serves as firm evidence to demonstrate the underlying mechanism of stabilized deep-ultraviolet random laser action that multiple scattering of a light beam in a disordered medium can induce Anderson localization similar to electron behavior. This feature covers the whole spectral range, and it is a universal phenomenon of an electromagnetic wave. Notably, stabilized deep-ultraviolet random laser action has not been demonstrated in all previous studies, even though it has great academic interest and potential application in many areas from environmental protection to biomedical engineering.

Light emitting diodes (LEDs) are ubiquitous in our daily life nowadays. Among them, ultraviolet LEDs are unique because of their wide range of potential applications, spanning from biomedicine, environmental protection to public health. However, fabricating highly efficient and cost-effective ultraviolet LEDs still remains as a great challenge. In this work, a graphene–insulator–semiconductor (GIS) ultraviolet LED based on the mechanism of quantum tunneling has been designed, fabricated, and demonstrated, which possesses state-of-the-art multi-purposes, including electroluminescence, outstanding detection performance, and economical fabrication processes. The GIS ultraviolet device consists of an AlGaN thin film, a SiO2 insulating layer, and a graphene transparent electrode. Under a forward bias, the electroluminescence can be induced by the recombination of hole tunneling from graphene into the valence band edge of n-AlGaN and electrons in the conduction band with a high emission efficiency exceeding 10%. In addition, our GIS ultraviolet LEDs show an excellent ultraviolet-detecting capability and dual-side light emission, which can be used in optical communications and for the development of multifunctional optoelectronic devices. Notably, unlike the conventional LEDs, which requires both p-type and n-type doping of a semiconductor, the developed approach shown here only needs one type of doping. This approach can be applied to many other semiconductors with the inherent difficulty of both type of doping.