Depth resolved carrier lifetime measurements of proton irradiated thyristors

Depth-resolved carrier lifetime profiles of proton-irradiated thyristors have been derived using a noncontact, optical pump/probe method. The results show that the depth distribution of recombination centra is sharply peaked at the ion range, although a significant tail extends towards the surface. Thus, the derived profiles exhibit an almost one-to-one correlation to the proton vacancy production rate. Furthermore, the lifetime in the tail scales inversely with ion fluence. Annealing studies, comparing the decrease in the rate of recombination at increasing temperature with deep level transient spectroscopy (DLTS) measurements, further support the notion that active recombination centra, produced by the proton irradiation, are mainly vacancy related. The annealing studies show that active recombination centra are relatively stable up to approximately 150 degrees C and only a 10-30% reduction occurs up to 300 degrees C. >