Failure analysis of aged GaAs HEMTs

High electron mobility transistor (HEMT) devices from three manufacturers were subjected to accelerated life tests. The purpose of the reliability studies of commercially available gallium arsenide signal transistors was to independently assess their state of maturity for use in spaceborne RF systems. HEMTs were examined from three manufacturers. The authors have completed detailed failure analyses of both aged and control HEMTs and have correlated the observations with the data on electrical performance. Analysis of parametric and catastrophic failures and accompanying control samples using a scanning electron microscope showed that failure was due to large defects near the gate region which enabled current to bypass the gate. The authors suggest that these large surface defects originated as subsurface point defects.<>