THE EFFECTS OF IONIZING RADIATION ON TRANSISTORS.
JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB
Pagination or Media Count:
An experiment, in which 15 npn bipolar silicon transistors were exposed to Co60 gamma radiation, is described. The known theory concerning the radiation damage of transistors is presented. In addition, the distinguishing characteristics of ionizing radiation damage are discussed, and a method of estimating bulk damage is developed. During the experiment, the following transistor parameters were measured AC and DC common emitter current gain, collector-to-base leakage current, gain-bandwidth product, and base spreading resistance. The damage curves for leakage current and AC and DC common emitter current gain are plotted and discussed. The relation between transistor parameter degradation and bias current is investigated by dividing the transistors into three equal groups and biasing them at three different collector levels during irradiation. The recovery of leakage current is plotted and an exponential curve fitted to the data. Recovery time of current gain is qualitatively observed. Data indicate that in some transistors damage to leakage current peaks near an accumulated radiation dose of 100,000 rad. The value of this peak is as large as 300 times the final damage value. The recovery time constant of leakage current damage is less than 15 minutes for the transistors tested. Author
- Electrical and Electronic Equipment
- Radioactivity, Radioactive Wastes and Fission Products