Operation of microwave Gunn devices under the influence of nuclear radiation

Radiation effects on the electrical properties of Gunn diodes have been studied in detail. A computer model has been carried out to study these effects on the transient characteristics (mobility, domain excess field and potential and the outside domain electric field). Also, the waveforms of current as a function of time for the oscillating diode has been obtained for different neutron fluences up to 2 x 1014 n/cm2. Experimental studies show that the operating frequency of the microwave oscillator is a direct linear function of the γ-exposure, up to a dose of 600 krad. In addition, severe interruption of the power characteristics, due to γ-irradiation is shown where the maximum output power peak was decreased while the bias, which is required to maintain power at peak point, is shown to be shifted towards high voltages. Finally, oven annealing of the irradiated samples at 150oC for 3 h shows that the recovery of characteristics is satisfactory. (Author)