Atomic layer deposition of Al2O3 and SiO2 on BN particles using sequential surface reactions

Al2O3 and SiO2 were deposited on BN particles with atomic layer control using alternating exposures of Al(CH3)(3)/H2O and SiCl4/H2O, 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 BNH2* surface species. These species reacted with Al(CH3)(3) or SiCl4 and were converted to AlCH3* or SiCl* surface species. The subsequent reaction with H2O converted the surface species to AlOH* or SiOH *. By repeating the sequential surface reactions, the absorbance of Al2O3 and SiO2 bulk vibrational modes on the BN particles increased vs, the number of reaction cycles. Transmission electron microscopy (TEM) studies revealed extremely uniform and conformal Al2O3 coatings on the BN particles. X-ray photoelectron spectroscopy (XPS) analysis was consistent with conformal Al2O3 coatings. In contrast, TEM investigations observed fairly uniform SiO2 coatings on the edge planes of the BN particles and only patches of SiO2 on the basal planes. XPS measurements were consistent with some uncovered regions on the SiO2-coated BN particles. These results illustrate the capability of sequential surface reactions to deposit ultrathin Al2O3 and SiO2 films on BN particles. (C) 2000 Elsevier Science B.V. All rights reserved.