Impact of 20-MeV /spl alpha/-ray irradiation on the V-band performance of AlGaAs pseudomorphic HEMTs

The irradiation damage in Si-planar-doped AlGaAs pseudomorphic HEMT's integrated in 50 GHz monolithic microwave integrated circuits (MMIC's) and subjected to 20-MeV /spl alpha/ and /spl gamma/-ray irradiation is studied. Both the static and the high frequency device parameters have been analyzed. It is shown that the drain current and the effective mobility decrease after irradiation, while the threshold voltage shifts in a positive direction. The degradation of the device performance increases for higher fluence. The decrease of the mobility is thought to result from the scattering of channel electrons by the induced lattice defects and also from the decrease of the electron density in the two dimensional electron gas (2DEG) region. Moreover, the noise figure increases with increasing fluence, while the gain decreases. After 150/spl deg/C post-irradiation thermal annealing for 15 min, the noise figure and gain for 1/spl times/10/sup 12/ /spl alpha//cm/sup 2/ recovers by 67 and 19%, respectively.