GE SEGREGATION IN SIGE SI HETEROSTRUCTURES AND ITS DEPENDENCE ON DEPOSITION TECHNIQUE AND GROWTH ATMOSPHERE/

Ge segregation at SiGe/Si heterointerfaces has been studied for films deposited by atmospheric pressure chemical vapor deposition (APCVD), u ltrahigh vacuum CVD (UHV/CVD) and molecular beam epitaxy (MBE). Profil es were taken by secondary-ion-mass-spectroscopy (SIMS) of samples gro wn with these techniques at the same growth temperatures and Ge concen trations. The MBE grown profiles are dominated by segregation of Ge in to the Si top layer in the temperature range from 450 to 800-degrees-C . SiGe/Si interfaces deposited by UHV/CVD at elevated temperatures are smeared, but at 515-degrees-C and below the interfaces are abrupt wit hin the resolution of the SIMS. Heterostructures grown by APCVD show a brupt interfaces and no indication of Ge segregation in the investigat ed temperature range from 600 to 800-degrees-C. Surface passivation by hydrogen appears to be responsible for the suppression of the Ge segr egation in CVD processes.