Reliability Study of GaAs FET.
Abstract
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 (Ti/Cr/Pt/Au). 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-Ge/Pt Ohmic contacts, failed because of increasing parasitic resistance; they failed faster than the Type-A FETs, with Au-Ge/Ni 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1978
- Accession Number
- ADA061473
Entities
People
- R. Lundgren
Organizations
- HRL Laboratories