Reliability aspects of commercial AlGaAs/GaAs HEMTs

The reliability of commercially available AlGaAs/GaAs HEMTs four different suppliers has been investigated by means of high temperature storage tests and biased life test. The main reliability problems have been detected in Schottky gate and ohmic contacts due to thermally activated metal-metal and metal-semiconductor interactions. In particular, Al/Ti gate contacts show a decrease of barrier height with the activation energy E/sub a/=1.3 eV, while Al/Ni Schottky contact shows an increase of barrier height with E/sub a/=1.8 eV. An increase of source and drain parasitic resistances has been detected in devices of two suppliers with E/sub a/=1.6 eV. Comparison with tests on low-noise MESFETs does not show major reliability problems for heterostructure devices.<
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