SURFACE-COMPOSITION OF ALN POWDERS STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY AND BREMSSTRAHLUNG-EXCITED AUGER-ELECTRON SPECTROSCOPY

The surfaces of AlN powders, which are particularly sensitive to moisture and atmospheric oxygen, are characterized by x-ray photoelectron spectroscopy (XPS). The powders used were exposed to ambient air and then heat treated at 100-degrees-C in air, argon, or nitrogen gas. Bremsstrahlung-excited Auger electron spectroscopy was used in combination with XPS to distinguish aluminum hydroxide from aluminum nitride on powder surfaces. The Auger peaks due to aluminum hydroxide and aluminum nitride were successfully resolved. The predominant surface oxygen-containing species was found to be aluminum hydrate with a composition near Al(OH)3, AlOOH, or a mixture of them, depending on the heat treatment employed. Such data are useful in understanding the feedstock surface chemistry involved in the fabrication of AlN ceramics.