In-situ epitaxial growth of heavily phosphorus doped SiGe by low pressure chemical vapor deposition

We have studied epitaxial crystal growth of Si _1-xGe _x films on silicon substrates at 550 °C by low pressure chemical vapor deposition. In a low PH ₃ partial pressure region such as below 1.25×10 ^-3 Pa, both the phosphorus and carrier concentrations increased with increasing PH ₃ partial pressure, but the deposition rate and the Ge fraction remained constant. In a higher PH ₃ partial pressure region, the deposition rate, the phosphorus concentration, and the carrier concentration decreased, while the Ge fraction increased. These suggest that high surface coverage of phosphorus suppresses both SiH ⁴ and GeH ₄ adsorption/reactions on the surfaces, and its suppression effect on SiH ₄ is actually much stronger than on GeH ₄. In particular, epitaxial crystal growth is largely controlled by surface coverage effect of phosphorus in a higher PH ₃ partial pressure region.