Atomic layer deposition of Al 2O 3 and SiO 2 on BN particles using sequential surface reactions

Abstract

Al 2O 3 and SiO 2 were deposited on BN particles with atomic layer control using alternating exposures of Al(CH 3) 3/H 2O and SiCl 4/H 2O, respectively. The sequential surface chemistry was monitored in vacuum using transmission Fourier transform infrared (FTIR) spectroscopy studies on high surface area BN particles. The initial BN particles displayed vibrational modes consistent with BOH* and BNH 2* surface species. These species reacted with Al(CH 3) 3 or SiCl 4 and were converted to AlCH 3* or SiCl* surface species. The subsequent reaction with H 2O converted the surface species to AlOH* or SiOH*. By repeating the sequential surface reactions, the absorbance of Al 2O 3 and SiO 2 bulk vibrational modes on the BN particles increased vs. the number of reaction cycles. Transmission electron microscopy (TEM) studies revealed extremely uniform and conformal Al 2O 3 coatings on the BN particles. X-ray photoelectron spectroscopy (XPS) analysis was consistent with conformal Al 2O 3 coatings. In contrast, TEM investigations observed fairly uniform SiO 2 coatings on the edge planes of the BN particles and only patches of SiO 2 on the basal planes. XPS measurements were consistent with some uncovered regions on the SiO 2-coated BN particles. These results illustrate the capability of sequential surface reactions to deposit ultrathin Al 2O 3 and SiO 2 films on BN particles.