Langmuir-Type Mechanism for In-Situ Doping in CVD Silicon-Germanium Epitaxial Growth

In-situ doping process of B and P in CVD Si, Si1-xGex and Ge epitaxial growth is reviewed using a modified Langmuir-type mechanism. For lower dopant gas (B2H6 or PH3) partial pressure, growth rate, Ge fraction and dopant (B or P) concentration in the films are explained by a Langmuir-type mechanism. For higher B2H6 gas partial pressure, it is proposed that SiH4, GeH4 and B2H6 molecules are absorbed and react partially at the B-occupied sites where B2H6 molecules have been adsorbed on (100) surface. For higher PH3 gas partial pressure, it is proposed that GeH4 molecules decomposes and PH3 molecules are adsorbed at the P-occupied sites and that P atoms are incorporated into the grown film according to the Henry's law. Fairly good agreement is obtained between all experimental data and the modified Langmuir-type mechanism for in-situ doping.