Failure Mechanisms and Reliability of Low-Noise GaAs FETs

A comprehensive reliability study of low noise GaAs FETs is presented. It involves over 1500 devices and 1,500,000 device hours of aging and various conditions of elevated temperature, bias and humidity. The major findings are: a) The Al gate metallization is responsible for the major failure mechanisms. Proper design and packaging can circumvent these problems. b) Unbiased aging leads to meaningless and overly optimistic results. c) DC and RF degradation generally do not agree and contact degradation is not accompanied by a loss of RF performance. d) A properly designed low noise GaAs FET can have failure rates comparable to those reported for silicon devices of similar size.