Stress reduction and doping efficiency in B- and Ge-doped silicon molecular beam epitaxy films

Abstract
Lattice defects in boron highly doped silicon molecular beam epitaxy films (B:2×1020 cm−3) were reduced by a simultaneous doping of germanium and boron. The defect reduction mechanism was investigated with surface defect observation, x-ray diffraction, and Raman spectroscopy. The growth rate of Si and the doping level of Ge and B were controlled precisely, and the suitable germanium-to-boron ratio was determined. At a germanium-to-boron ratio of 4:1, a drastic decrease of the defect density was observed, and the doping efficiency was improved.