Antimony segregation and n-type doping in Si/Si(111) films grown by molecular beam epitaxy

The temperature dependence of antimony segregation in Si/Si(111) films grown by molecular-beam epitaxy was investigated experimentally. The obtained results were found to be qualitatively similar to the previously reported data for Si(001) case, but rather significant quantitative differences were observed. It was obtained that segregation ratio, which is defined as surface-to-bulk impurity concentration ratio, varies by nearly 5 orders of magnitude in the relatively narrow temperature interval of 500-675 °C for Si(111). This finding allowed to disseminate the previously proposed technique of selective doping of Si(001) to the Si(111) case. Using this technique selectively n-type doped Si films were fabricated which have abrupt boundaries of the antimony concentration profiles. A profile abruptness as low as 1.5 nm/decade was obtained.