Reliability of High Frequency High Power GaAs MESFETs

Two types of microwave high power GaAs MES FETs of FUJITSU "2" series have been accelerated stress tested up to 10,000 hours-duration time under RE operation at 8 GHz with elevated temperatures between 210 deg-C and 250 deg-C. The purpose of this test was to estimate MITFs of the GaAs FETs and to verify that "2" series GaAs FETs have sufficient life for space application. The failure mode identified was void formation in the gate electrodes inside the active area. The voids were created even in the condition of relatively low gate current density. The activation energy and MTTF of the void formation were estimated. Effect of gate width on MITF is discussed and a relationship between MTTF and gate width is derived from Weibull function.