STRUCTURE AND CHEMICAL-COMPOSITION OF BN THIN-FILMS GROWN BY PULSED-LASER DEPOSITION

BN thin films were produced by pulsed laser deposition from a sintered BN target of the hexagonal structural phase using XeCl excimer laser radiation (lambda = 308 nm) or pulsed CO2 laser radiation (lambda = 10 .6 mu m), and varying the process variables (laser fluence, N-2 partia l pressure, target-substrate distance). Film properties such as chemic al composition and crystal structure were studied by ex situ X-ray pho toelectron, Auger electron and micro-Raman spectroscopies. Simple ther modynamic arguments are given to explain aspects of material removal f rom the target and film deposition. Films are generally composed of a fine-grained matrix in which particles 10-15 mu m (lambda = 308 nm) or 10-100 mu m (lambda = 10.6 mu m) in size are embedded. In addition to BN, the films contain contaminants B2O3, metallic B, and a boron-oxyn itride species, with the relative proportions dependent on the lateral position on the film surface. Micro-Raman spectra give evidence of am orphous and hexagonal structural phases of the BN matrix material.