Investigation of the interface integrity on the thermally stable WN/GaAs Schottky contacts

WNx/GaAs Schottky contacts formed by reactive sputtering have been found to be thermally stable up to an annealing temperature of ∼900 degrees C. The interface morphology and structure of this contact under high temperature annealing conditions have been investigated by transmission electron microscopy (TEM) and x-ray diffractometry. The contact interface remained thermally stable up to 850 degrees C. Cross-sectional TEM micrographs revealed that annealing at temperatures above 850 degrees C resulted in the formation of pockets beneath the interface. This phenomenon has been correlated with the electrical properties of the contacts. Comparisons between the interface morphology of this system and other refractory metal nitride contacts are also presented