OPERATION OF MICROWAVE GUNN DEVICES UNDER THE INFLUENCE OF NUCLEAR RADIATION

Radiation effects on the electrical properties of Gunn diodes have bee n studied in detail. A computer model has been carried out to study th ese 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 h as been obtained for different neutron fluences up to 2 x 10(14) n/cm( 2). Experimental studies show that the operating frequency of the micr owave oscillator is a direct linear function of the gamma-exposure, up to a dose of 600 krad. In addition, severe interruption of the power characteristics, due to gamma-irradiation is shown where the maximum o utput power peak was decreased while the bias, which is required to ma intain power at peak point, is shown to be shifted towards higher volt ages. Finally, oven annealing of the irradiated samples at 150 degrees C for 3 h shows that the recovery of characteristics is satisfactory.