QUASI-MEDIUM ENERGY ION-SCATTERING SPECTROSCOPY OBSERVATION OF SURFACE SEGREGATION OF GE DELTA-DOPED LAYER DURING SI MOLECULAR-BEAM EPITAXY

We have observed the behavior of Ge delta-doped layers fabricated by m olecular beam epitaxy (MBE) on an Si(001) substrate and the surface se gregation of Ge atoms from delta-doped layers during a top Si buffer l ayer growth using quasi-medium energy ion scattering spectroscopy. We have found that the Ge atoms segregate to the surface even at a low su bstrate temperature of 300 degrees C. This result is in contrast to th e solid phase epitaxy case where Ge atoms diffuse around the interface . For MBE growth, at a substrate temperature of 600 degrees C, the sur face segregation was reduced. The distribution of Ge atoms is widely s pread in the subsurface region. This result indicates that the Ge atom s are incorporated in the Si buffer layer with mixing by Si atoms. (C) 1997 Elsevier Science B.V.