In-situ observation of Ge δ-layer in Si(001) using quasi medium energy ion scattering spectroscopy

We have performed in-situ observation of Ge delta-layers in Si(001) fabricated by different methods, using quasi medium energy ion scattering spectroscopy. The following has been revealed: (1) the Ge atoms segregate to the surface even at a low substrate temperature of 200 degrees C during MBE growth of Si buffer layer. (2) In the delta-layers fabricated by hydrogen mediated epitaxy, the surface segregation of Ge atoms was reduced compared with that by conventional MBE. The Ge atoms, however, were widely spread in the growing film. Hydrogen atoms are segregated to the topmost layer of the growth surface. (3) In a solid phase epitaxy (SPE) case, Ge atoms are confined and diffuse around the interface. For realizing delta-layer structure of doping atoms such as Ge, which are strongly segregated on the growth front, SPE is found to be an effective method. (C) 1999 Elsevier Science Ltd. All rights reserved.