Direct growth of hexagonal boron nitride films on dielectric sapphire substrates by pulsed laser deposition for optoelectronic applications

Abstract

Recently, hexagonal boron nitride (h-BN), an ultra-wide bandgap semiconductor, has attracted considerable attention owing to its excellent properties. In thin films grown on metal catalysts, contamination and damage induced by a transfer process cannot be avoided. Therefore, synthesizing h-BN films on non-catalytic dielectric substrates is desirable for electronic applications. In this study, we demonstrate the direct growth of high-quality h-BN films with a controllable thickness on sapphire substrates by using the pulsed laser deposition (PLD) technique. The effects of the deposition conditions and laser parameters on the growth of the h-BN films are systematically investigated by evaluating their characteristic Raman peaks. Among the various growth parameters studied, the substrate temperature has the greatest influence on the crystalline quality of the h-BN films, and the optimal pressure varies depending on the target-substrate distance. The h-BN film grown under optimal conditions exhibits a narrow Raman line width of ∼30 cm−1, indicating a high crystalline quality. The photodetectors fabricated from the PLD-grown h-BN films exhibit superior deep-ultraviolet detection performance with a large on/off ratio of >104, high photoresponsivity, and a sharp cut-off wavelength of 220 nm. This study presents the possibility of producing high-quality h-BN films by applying PLD on dielectric substrates for optoelectronic applications.