An investigation was made of 2.5MeV irradiation-induced deep levels in 6H-type p+n diodes which had been prepared by means of chemical vapor deposition. Deep-level transient spectroscopy revealed several overlapping peaks at temperatures ranging from 140 to 650K. It was shown that the amplitudes of the deep-level transient spectroscopy peaks, E1 and E2, were significantly reduced when both holes and electrons were injected into the space-charge region. This reduction in peak amplitude occurred if the E1 and E2 centers acted as efficient hole-electron recombination centers. Due to this behavior, it was suggested that the E1 and E2 centers might be important during recombination in irradiated material. However, these two centers did not govern the minority carrier lifetime. The temperature dependence of the electron capture cross-section was measured for the E1, E2 and Ei levels. Two of these, E1 and E2, exhibited a weak temperature dependence. On the basis of their small electron-capture cross-sections, and the absence of a Poole-Frenkel effect, it was suggested that E1 and E2 were associated with neutral acceptor-like centers. The electron-capture cross-section of the Ei level was shown to be temperature-independent at temperatures ranging from 248 to 275K.

C.Hemmingsson, N.T.Son, O.Kordina, E.Janzén, J.L.Lindström: Journal of Applied Physics, 1998, 84[2], 704-8