Low-high-low profile gallium arsenide IMPATT reliability

The reliability of low-high-low gallium arsenide IMPATT diodes has been studied. The devices were fabricated from vapor phase grown epitaxial gallium arsenide using sputtered platinum Schottky junctions and plated heat sink construction. Various screening methods have been evaluated for use in burn-in, and 75°C case dc burn-in at rated power dissipation selected as the best compromise. Long-term operation tests have established a minimum MTBF at 90-percent confidence of 34 000 h. RF and storage step stress tests have revealed a potential failure mechanism involving separation of the metallization layers. An improved metallization system has been established eliminating this mechanism. Various additional tests have demonstrated the immunity of these IMPATT's to damage from on-off switching transients, load mismatch, and bias voltage transients.