Radiation Damage in GaAs Gunn Diodes

Both pulsed and CW GaAs Gunn oscillator diodes, wit initial carrier concentrations between 3.3 × 1014 cm-3 & 1.5 × 1015 cm-3 were irradiated in a series of steps to total accumlated neutron fluences as high as 1.12 × 1014n · cm-2 (E¿10 keV). A low field I-V point was determined, and the frequency and output power were measured at the operating voltage for each device. Carrier removal rates were determined from the low-field resistance. Values ranged betwreen 3.57 cm-1 and 10.3 cm-1 for these devices and were found to vary as the 0.4 power of the initial carrier concentration. Output power ultimately decreased with increasing fluence, with device failure occurring between 2.4 × 1013 n · cm-2 and about 1 × 1014n · cm-2 , increasing fairly linearly with the initial carrier concentration. The carrier concentration at device failure also depends linearly on the initial concentration.