A variable temperature x-ray photoelectron spectroscopic study of the surface conversion of diethylaluminum azide to AlN

Abstract

Variable temperature x-ray photoelectron spectroscopy was used to study the thermal reaction of condensed thin films of diethylaluminum azide, yielding AlN. This precursor has been shown to be a useful chemical vapor deposition (CVD) reagent for the preparation of AlN thin films by a thermally assisted CVD process. Reaction progress was monitored easily with x-ray photoelectron spectroscopy (XPS) due to the chemical uniqueness and thus the spectral uniqueness of the various functionalities in the molecule. The results are consistent with a mechanism proposed in other studies. They indicate commencement of the surface reaction at about 300 °C and formation of AlN at temperatures above 500 °C. Activation of the diethylaluminum azide by various means causes the elimination of molecular nitrogen concomitant with the formation of an intermediate which is suggested to be a nitrene radical. This intermediate is found to have a high desorption energy, and, its subsequent reaction to yield AlN is confined to the surface.