Low-Temperature Deposition of Hexagonal Boron Nitride via Sequential Injection of Triethylboron and N2/H2 Plasma

Abstract

Hexagonal boron nitride (hBN) thin films were deposited on silicon and quartz substrates using sequential exposures of triethylboron and N 2 /H 2 plasma in a hollow-cathode plasma- assisted atomic layer deposition reactor at low temperatures ( ≤ 450 ° C). A non-saturating film deposition rate was observed for substrate temperatures above 250 ° C. BN films were charac- terized for their chemical composition, crystallinity, surface morphology, and optical properties. X-ray photoelectron spec- troscopy (XPS) depicted the peaks of boron, nitrogen, carbon, and oxygen at the film surface. B 1s and N 1s high-resolution XPS spectra confirmed the presence of BN with peaks located at 190.8 and 398.3 eV, respectively. As deposited films were polycrystalline, single-phase hBN irrespective of the deposition temperature. Absorption spectra exhibited an optical band edge at ~ 5.25 eV and an optical transmittance greater than 90% in the visible region of the spectrum. Refractive index of the hBN film deposited at 450 ° C was 1.60 at 550 nm, which increased to 1.64 after postdeposition annealing at 800 ° C for 30 min. These results represent the first demonstration of hBN deposi- tion using low-temperature hollow-cathode plasma-assisted sequential deposition technique. © 2014 The American Ceramic Society.