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InP based LM-HEMTs are stressed at room temperature in a minute timeframe. Depending on the applied DC bias, various failure mechanisms are favorised. Their influence on the device characteristics is measured and analysed. A significant change in the DC and HF parameters has been noticed when stressed in the impact ionization region, which is not recoverable. However, after stress in the avalanche region only the gate leakage current increased and this is recoverable after a few minutes. During stress in both regions, the gate current Igsand the drain current Idsvary on a logaritmic time scale. This enlightens the importance of possible influence of standard on-wafer DC and HF characterizations on the device performance.

A general method to compensate for differences in probe-tip-to-line geometry and substrate permittivity between measurements and the calibration wafer is presented. The propagation constant, characteristic impedance and parameters of a general lumped-element equivalent discontinuity model are extracted at each frequency point based on measurements of two lines with different lengths.