Heavy atomic-layer doping of nitrogen in Si_(1-x)Ge_x film epitaxially grown on Si(100) by ultraclean low-pressure CVD

摘要

N atomic-layer doping in a nanometer-order Si/Si_(1-x)Ge_x/Si(100) heterostructure using ultraclean low-pressure chemical vapor deposition and its thermal stability at 650 ℃ were investigated. In the Si_(0.5)Ge_(0.5) epitaxial layer, it is found that a N doping dose of 6×10~(14) cm~(-2) can be confined within an about 1.5 nm-thick region even after 650 ℃ heat treatment in contrast to the result for Si cap layer growth on the thermally nitrided Si(100) with a N doping dose of 6×10~(14)cm~(-2) which was found to be amorphous. Moreover, it is suggested that the confined N atoms in Si_(1-x)Ge_x preferentially form Si-N bonds and that formation of Si_3N_4 is enhanced by the heat treatment at 650 ℃.