Langmuir-Type Mechanism for In-Situ Boron Doping in CVD Si1-xGex Epitaxial Growth

High performance Si-based devices require atomically ordered interface of heterostructures and doping profiles as well as strain engineering due to the introduction of Ge into Si. In this work, in-site B doping in CVD Si and Si_1-xGe_x epitaxial growth is formulated based on the Langmuir-type surface adsorption and reaction scheme. Anomalous heavy B doping and the increase of growth rate with B₂H₆ addition are explained, assuming that SiH₄, GeH₄ and B₂H₆ adsorb/react partially at the sites where B₂H₆ molecules have been adsorbed on (100) surface. Fairly good agreement is obtained between all experimental data and the modified Langmuir-type mechanism for in-situ B doping.