REACTIONS OF TRIMETHYLALUMINUM AND AMMONIA ON ALUMINA AT 600-K - SURFACE CHEMICAL ASPECTS OF ALN THIN-FILM GROWTH

The reactions of trimethylaluminum (TMAl) and ammonia (NH3) on gamma-alumina at 600 K were studied by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) to explore fundamental issues of AlN film growth. FTIR and XPS assignments for surface species present after the deposition process have been directly correlated from measurements taken in the same instrument. Sequential exposure of TMAl and NH3 leads to self-limiting adsorption of TMAl and site-selective reaction with NH3 to form a thin layer of AlN along with dinitrogen and NH2 species. The coexposure of TMAl and NH3 leads to continuous deposition resulting in a thick film of AlN with NH2 and dinitrogen species present at the AlN/alumina interface and NH terminating the AlN/vacuum interface. These processes are discussed in terms of AlN thin film growth strategies.