Effect of heavy in-situ phosphorus doping on Si1-xGex epitaxial growth by low-pressure chemical-vapor deposition

We have studied the effect of in-situ phosphorus doping on Si1-xGex films w ith a high Ge fraction grown on silicon substrates at 550 degreesC by using low-pressure chemical-vapor deposition. In a low PH3 partial pressure regi on, such as below 1.25x10(-3) Pa, both the phosphorus and the carrier conce ntrations increased with increasing PH3 pressure, but the deposition rate a nd the Ge fraction remained constant. In a higher PH3 partial pressure regi on, the deposition rate, the phosphorus concentration, and the carrier conc entration decreased while the Ge fraction increased. Moreover, the depositi on rate and the Ge fraction increased with increasing GeH4 partial pressure while the phosphorus and carrier concentrations decreased. Si1-xGex epitax ial growth is largely controlled by the surface coverage effect of phosphor us in a higher PH3 partial pressure region, but it is controlled the Langmu ir-adsorption-type kinetics in a lower pressure region.