Position lifetime measurements were performed on bulk SixGe1-x crystals, and it was found that the bulk lifetimes varied between those for Ge and Si. The dependence of the lifetime upon the composition exhibited a sudden change at x-values of between 0.17 and 0.20. This appeared to be related to changes in the band-gap energy. After 3MeV electron irradiation, vacancy-type defects which gave rise to lifetimes of about 280 and 330ps were detected at x-values of between 0.63 and 0.82 and between 0.20 and 0.40, respectively. They were not found at an x-value of 0.17. The composition-dependence of the vacancy production was explained in terms of the thermal stability of vacancies as a function of composition.

A.Kawasuso, S.Okada, M.Suezawa, T.Honda, I.Yonenaga: Journal of Applied Physics, 1997, 81[6], 2916-8