Reliability Study of GaAs FET.
Final technical rept. 30 Jun 76-Apr 78,
HUGHES RESEARCH LABS MALIBU CALIF
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The reliability of three types of low-noise GaAs field-effect transistor FET or MESFET was investigated. Types A and B incorporate Al Schottky-barrier gates Type C has a gold gate structure TiCrPtAu. FETs were tested to determine the ability of their gates to withstand electrical stress. Catastrophic failure occurred at approximately 3 ergs and 0.8 ergs input energy for positive and negative dc pulses, respectively contrary to other reports, the Au-gate devices were not more robust. With either cw or pulsed rf stress, the Type-A devices failed at between 1 and 3 W. Constant-stress accelerated life tests were performed at temperatures between 200 C and 245 C, using both unbiased and dc-biased samples. The biased gold-gate devices failed relatively early because of electrical degradation of their gates. The Type-B devices, with Au-GePt Ohmic contacts, failed because of increasing parasitic resistance they failed faster than the Type-A FETs, with Au-GeNi contacts. The biased Type-A samples failed because of structural changes in the Al gate a poor SiO2 glassivation layer is suspected to be the cause. Author
- Electrical and Electronic Equipment
- Manufacturing and Industrial Engineering and Control of Production Systems
- Solid State Physics