GROWTH TEMPERATURE-DEPENDENCE OF BORON SURFACE SEGREGATION AND ELECTRICAL-PROPERTIES OF BORON DELTA-DOPED STRUCTURES GROWN BY SI MOLECULAR-BEAM EPITAXY

Reflection high-energy electron diffraction (RHEED) intensity oscillat ion showed a 4-monolayer (ML) period in the early stage of Si molecula r beam epitaxy (MBE) on a 1 ML boron preadsorbed Si(111) surface, as l ong as the surface-segregated boron coverage was more than 1/3 ML. Tem perature dependence of the boron surface segregation was investigated from the duration of the 4-ML-period oscillation. Effective solubility of boron in Si was one order higher than those reported for 1/3 ML bo ron preadsorbed cases. Crystallinity of the Si overlayer was satisfact ory when the growth temperature was equal to or above 450 degrees C, a nd 2/3 of the initially adsorbed boron atoms were confined to within a bout 10 ML (about 16 Angstrom) of tile Si overlayer at 450 degrees C. Boron preadsorption was found to saturate at 1 ML, and the temperature dependence of the peak carrier concentration showed the same tendency as that of the effective solubility.