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Gold specimens of nominal 99.9999% purity were irradiated with 3-MeV electrons near liquid-nitrogen temperature. The damage production rate is found to depend on the purity of the specimen giving a lower value for the high-purity specimens. It is also found that the production rate is reduced remarkably by quenching the specimen before irradiation. For high-purity gold, a single large annealing peak is observed in stage III. The slope-change method and Primak analysis are employed to obtain the activation energy of stage-Ill annealing. Both methods give 0.85=1=0.02 eV for the activation energy in high-purity irradiated specimens. The activation energies for quenched and for quench-plus-irradiated specimens of comparable purity are found to be 0.85=1=0.03 and 0.86±0.02 eV, respectively, agreeing with the value for the irradiated specimens within the experimental error. Somewhat lower values are obtained for specimens of lower purity. Second-order kinetics are obeyed in the main part of the stage-Ill annealing for the irradiated, quench-plus-irradiated, and quenched specimens. Various models are discussed to explain stage-Ill annealing. It is concluded that vacancy migration in stage III with interstitial clusters acting as sinks can account for the observed results most satisfactorily in the case of gold.

We present the experimental results on the three-terminal on-state and off-state breakdown voltage studies of recessed-gate GaN MESFETs. Typical values of BVDG=57 V and BV,,= 46 V for the off-state breakdown voltages (BV) were measured at a value of current I, = -0.05 mA/mm. On-state BV measurements were carried out at constant extracted gate current values of I,= -0.01 mA/mm and -0.05 mA/mm with the drain current being swept from I,= I I, I (offstate) to I,= 5 mA/mm (on-state). The values for BVo, loci at I, = I I, I (off-state) match the results for the off-state BV measurements. In addition, a collapse of the I-V curves characterized by suppressed drain currents was observed after each BV experimental run, but the original I-V curves could be recovered after exposure to light from a blue LED. We relate the collapse of the drain current to the presence of electron traps.

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