Micron-Thick Hexagonal Boron Nitride Crystalline Film\nfor Vacuum Ultraviolet Photodetection with Improved Sensitivity and\nSpectral Response

Abstract

Hexagonal\nboron nitride crystalline film with a thickness of 70\nμm is deposited on a c-plane sapphire at 1700 °C by the\nchemical vapor deposition (CVD) method. In X-ray diffraction (XRD)\ncharacterizations, a peak of (002) is observed at 26.01° with\nthe full width at half-maximum (FWHM) of 1.17°, and the c-axis\nlattice constant is estimated to be 6.84 Å. The characterization\nresults of Raman and X-ray photoelectron spectroscopy further confirm\nthe film’s high quality. Based on the h-BN film, a vacuum ultraviolet\n(VUV) photodetector is further fabricated with a responsivity of 48.7\nμA/W, exhibiting a photo-to-dark current ratio (PDCR) of more\nthan 10³ as well as an excellent spectral selectivity to\nshort-wave ultraviolet irradiation. By analyzing the photoresponse\nprocess, the influence of different response mechanisms is explained,\nimplying the photodetector’s ability to respond quickly.