Selective Epitaxial Growth of Si and Si1-xGex Films by Ultrahigh-Vacuum Chemical Vapor Deposition Using Si2H6 and GeH4

Aiming at the precise profile control of Si1-x Ge x , selective epitaxial growth (SEG) conditions and Si1-x Ge x growth were investigated by ultrahigh-vacuum chemical vapor deposition (UHV-CVD) using Si2H6 and GeH4. As long as the total amount of Si2H6 did not exceed the critical amount, Si- and Si1-x Ge x -SEG were both achieved independent of source gas flow rate and substrate temperature. The Ge fraction x of Si1-x Ge x could be decided by the flow rate ratio between Si2H6 and GeH4, independent of substrate temperature. Fast gas flow switching realized the formation of a Si(120 Å)/Si1-x Ge x (69 Å) strained layer superlattice at 587°C.