Phosphorus doping in molecular beam epitaxial grown silicon and silicon/germanium using a GaP decomposition source

Abstract

Donor-doping in silicon molecular beam epitaxy (MBE) is still an open problem, due to the low solid solubility and the strong segregation behavior (Sb,As) or to the high vapor pressure of the doping elements (P,As). Based on its high solubility, elemental P 2 would be the best candidate for heavy n-type doping. A new source has been applied to incorporate electrically active phosphorus during growth higher than 10 20 cm −3 in Si and SiGe. The incorporation probabilities into Si and strained SiGe will be compared. The dependence of segregation/diffusion processes of phosphorus on growth temperature during the MBE will be shown. No surface accumulation of phosphorus or gallium were observed. SIMS investigations on undoped Si layers reveal no P or Ga “memory effect” of the UHV equipment.