Recently, the deep ultraviolet (DUV) photodetectors fabricated from two-dimensional (2D) hexagonal boron nitride (h-BN) layers have emerged as a hot research topic. However, the existing studies show that the h-BN-based photodetectors have relatively poor performance. In this work, C doping is utilized to modulate the properties of h-BN and improve the performance of the h-BN-based photodetectors. We synthesized the h-BN atomic layers with various C concentrations varying from 0 to 10.2 atom % by ion beam sputtering deposition through controlling the sputtering atmosphere. The h-BN phase remains stable when a small amount of C is incorporated into h-BN, whereas the introduction of a large amount of C impurities leads to the rapidly deteriorated crystallinity of h-BN. Furthermore, the DUV photodetectors based on C-doped h-BN layers were fabricated, and the h-BN-based photodetector with 7.5 atom % C exhibits the best performance with a responsivity of 9.2 mA·W–1, which is significantly higher than that of the intrinsic h-BN device. This work demonstrates that the C doping is a feasible and effective method for improving the performance of h-BN photodetectors.

Wide-band-gap layered semiconductor hexagonal boron nitride (h-BN) is attracting intense interest due to its unique optoelectronic properties and versatile applications in deep ultraviolet optoelectronic and two-dimensional electronic devices. However, it is still a great challenge to directly grow high-quality h-BN on dielectric substrates, and an extremely high substrate temperature or annealing is usually required. In this work, highquality few-layer h-BN is directly grown on sapphire substrates via ion beam sputtering deposition at a relatively low temperature of 700 °C by introducing NH 3 into the growth chamber. Such low growth temperature is attributed to the presence of abundant active N species, originating from the decomposition of NH 3 under ion beam irradiation. To further tailor the properties of h-BN, carbon was introduced into the h-BN layer by simultaneously introducing CH 4 and NH 3 during the growth process, indicating the wide applicability of this approach. Moreover, a deep ultraviolet (DUV) photodetector is also fabricated from a C-doped h-BN layer and exhibits superior performance compared with an intrinsic h-BN device.