A Power Law Model for Assessment of Hot Electron Reliability in GaAs MESFETs and AlGaAs/InGaAs pHEMTs
Val Kaper * , Peter Ersland
M/A-COM Engineering & Technology Group
100 Chelmsford Street; Lowell, MA 01851
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Hot electron reliability experiments were conducted on four GaAs FET processes. Observed device degradation was similar to the results reported by other authors (e.g. decrease of the open channel current, and a rightward shift and compression of the transconductance curve). While the degradation modes were the same for all four processes, the degradation rates were not. These results have led us to propose that the existing figure of merit model  should be extended to a power law model, thereby incorporating the dependence of device degradation rate on the reverse gate-drain current density. The power law model coefficients along with the breakdown voltage provide complete information about susceptibility of a particular process to the hot electron induced degradation, and also indicate reliability limitations on what type of dynamic load line and input power level can be safely used.