Chemical vapor deposition of sp2-boron nitride films on Al2O3 (0001), (112¯0), (11¯02), and (101¯0) substrates

Abstract

Thin films of boron nitride in its sp2-hybridized form (sp2-BN) have potential uses in UV devices and dielectrics. Here, we explore chemical vapor deposition (CVD) of sp2-BN on various cuts of sapphire: Al2O3 [Formula: see text], Al2O3 [Formula: see text], Al2O3 [Formula: see text], and Al2O3 (0001) using two CVD processes with two different boron precursors triethylborane and trimethylborane. Fourier transform infrared spectroscopy shows that sp2-BN grows on all the sapphire substrates; using x-ray diffraction, 2θ/ω diffractogram shows that only Al2O3 [Formula: see text] and Al2O3 (0001) rendered crystalline films: and using phi(ϕ)-scans, growth of the rhombohedral polytype (r-BN) films on these substrates is confirmed. These films were found to be epitaxially grown on an AlN interlayer with comparatively higher crystalline quality for the films grown on the Al2O3 [Formula: see text] substrate, which is determined using omega(ω)-scans. Our study suggests that Al2O3 [Formula: see text] is the most favorable sapphire substrate to realize the envisioned applications of r-BN films.