Deep-ultraviolet (DUV) photodetectors based on hexagonal boron nitride ( h-BN) have demonstrated great potentials for various commercial and military applications; however, to date, most studies show that the h-BN photodetectors suffer from poor performance, such as low responsivity and large dark current. Herein, we report the dramatic enhancement of photoresponse in the DUV region of a h-BN device coupled with plasmonic nanostructures of either h-BN nanosheets (BNNSs) or Au nanoparticles (NPs). Large-area h-BN thin films that have been directly grown on quartz substrates using the ion beam assistant deposition method exhibit a uniform thickness of ∼200 nm, an ultrawide bandgap (∼ 6 eV), and an excellent light transparency in the visible region. Based on the vertical charge transfer integrated with plasmonic nanoarrays, the photocurrent of the h-BN device can be greatly enhanced by up to about 7–9 times under the illumination of 205 nm by showing a cutoff wavelength at ∼220 nm. Owing to the retained low dark current and large photo-gain induced by localized plasmonic resonances, this hybrid photodetector exhibits 32- and 57-fold improvement in responsivity at a 205 nm wavelength by BNNSs and Au NPs, respectively. This work demonstrates plasmonic enhancement on optoelectronic properties of h-BN based on not only metallic but also semiconducting nanostructures and provides alternative pathways for the development of low-cost, large-area, high-performance, DUV photodetectors for various optoelectronic devices and security applications.

Effective doping of ultra-wide band gap semiconductors is of crucial importance, yet, remains challenging. Here, we report the enhancement of n-type conductivity of nanocrystalline hexagonal boron nitride (h-BN) films with simultaneous incorporation of Si and O while deposition by radio frequency (RF) magnetron sputtering method. The resultant h-BN films are of ~50 nm in thickness, containing nitrogen vacancy (VN) defects. Incorporation of O together with Si results in effective healing of VN defects and significantly reduces electric resistivity in h-BN thin films. X-ray photoelectron spectroscopy (XPS) results reveal that under B-rich condition, the substitutional O in VN bonding with B leads to the formation of Si-N, which thus plays an important role to the n-type conductivity in h-BN films. The temperature dependent electrical resistivity measurements of the Si/O co-doped h-BN films reveal two donor levels of 130 and 520 meV at room temperature and higher temperatures, respectively. The n-h-BN/p-Si heterojunctions demonstrate apparent rectification characteristics at room temperature, where the tunnelling behaviour dominates throughout the injection regimes due to the effective carrier doping. This work proposes an effective approach to enhance the n-type conductivity of h-BN thin films for future applications in electronics, optoelectronics and photovoltaics.