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Responses to 1.8 MeV proton irradiation and 10-keV X-ray irradiation under typical bias conditions are investigated for AlGaN/GaN HEMTs fabricated with different types of process technologies. We find that, in contrast to previous generations of process technologies, total ionizing dose effects can be significant in these devices. For proton irradiation, worst-case bias for transconductance degradation for GaN-on-SiC substrate devices is ON bias, and for devices built on free-standing GaN substrates, the worst-case bias condition is semi-ON bias. Low-frequency noise measurements demonstrate that these differences result from differences in defect types and energy distributions for the different types of devices, both before and after irradiation. These results emphasize the need to test devices under a wide range of conditions during characterization and qualification testing. [ABSTRACT FROM PUBLISHER]

A small degradation of threshold voltage and a significant reduction in dc and RF transconductance are observed for AlGaN/GaN high-electron-mobility transistors fabricated via three different process techniques and subjected to high voltage stress in the semi-ON bias condition. Low-frequency noise measurements as a function of temperature show peaks at ∼0.2, ∼0.5, ∼0.7, and/or ∼0.8 eV that increase with the magnitude and duration of high-field stress. The dehydrogenation of passivated Fe and O impurity defects and/or N antisite defects leads to increased charge trapping, noise, and transconductance degradation. Density functional theory calculations show that Ga vacancy motion and dehydrogenation of substitutional Fe complexes in the GaN buffer layer also contribute significantly to the poststress degradation of these devices. At higher stress voltages, these defects also likely contribute to device failure. [ABSTRACT FROM PUBLISHER]

AlGaN/GaN high electron mobility transistors (HEMTs) irradiated with 1.8-MeV protons show more relative degradation in RF power/current gain, cutoff frequency f_T, and maximum oscillation frequency fmax than DC transconductance. These result from radiation-induced increases in fast bulk and surface trap densities, as well as increasing impedance mismatch at high frequencies with increasing proton fluence. NH3-rich MBE devices show less degradation in DC transconductance, but more degradation in RF gain than Ga-rich devices. [ABSTRACT FROM PUBLISHER]

The responses to 1.8 MeV proton irradiation of AlGaN/GaN HEMTs grown under Ga-rich and ammonia-rich conditions are investigated in this work. Changes in defect energy distributions of AlGaN/GaN HEMTs during proton irradiation are characterized via temperature-dependent low-frequency noise measurements. Density functional theory calculations show these changes are consistent with the reconfiguration and/or dehydrogenation of oxygen-related defects in Ga-rich devices. [ABSTRACT FROM PUBLISHER]