Positron annihilation spectroscopic measurements were performed on Si layers which had been deposited, at temperatures of between 200 and 700C, using molecular beam epitaxy. The samples were annealed at between 400 and 700C. The positron annihilation spectroscopy showed, for the first time, that low-temperature Si contained very high densities (greater than 1018/cm3) of extremely large vacancy clusters (open space greater than 10 atoms). Because these vacancy clusters were considered to weaken the thin low-temperature Si layer, the formation of high-quality SiGe pseudo-substrates on low-temperature Si was described in terms of a strained compliant-substrate/epitaxial-film model.

Characterization of Low-Temperature Grown Si Layer for SiGe Pseudo-Substrates by Positron Annihilation Spectroscopy. T.Ueno, T.Irisawa, Y.Shiraki, A.Uedono, S.Tanigawa, R.Suzuki, T.Ohdaira, T.Mikado: Journal of Crystal Growth, 2001, 227-228, 761-5