A study was made of a photoluminescence spectrum which appeared after the room-temperature electron irradiation of 4H-type samples. The spectrum consisted of several sharp no-phonon lines, together with a broad phonon-assisted structure. Annealing at about 750C caused a sudden change in the spectrum. Further annealing steps occurred at temperatures above 750C, and eventually led to a predominance of a strong photoluminescence spectrum. The overall characteristics of the photoluminescence lines suggested that they were due to bound exciton recombination at iso-electronic defect centers.

Photoluminescence of Electron-Irradiated 4H-SiC. T.Egilsson, A.Henry, I.G.Ivanov, J.L.Lindström, E.Janzén: Physical Review B, 1999, 59[12], 8008-14