High‐spatial‐resolution scanning Auger spectroscopy applied to analysis of X‐band diode burnout

Low‐noise‐figure Schottky‐barrier mixer diodes for use at X‐band and above have small active areas and are thus susceptible to burnout or degradation from high rf power levels. As part of a program to improve burnout resistance of mixer diodes for a Navy system, metal diffusion couples were studied and diodes were fabricated, burned out, and analyzed. The microspot Auger analysis technique in the Auger‐spot mode provided the required submicron identification of the interdiffusion phenomena in the failed regions of the mixer diodes. For cw‐failed diodes, interdiffusion between the various diffusion couples found in both Pt–Ti–Mo–Au and Ti–Mo–Au diodes has been identified as the primary failure mode. In the pulsed case the lack of interdiffusion as made evident in the analysis of edge‐burned‐out sites indicates the existence of an alternate failure mode.