Plasmonic enhancement in deep ultraviolet photoresponse of hexagonal boron nitride thin films

Abstract

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.