Epitaxial growth of P atomic layer doped Si film by alternate surface reactions of PH_3 and Si_2H_6 on strained Si_(1-x)Ge_x/Si(1 0 0) in ultraclean low-pressure CVD

摘要

P atomic layer formation on Si_(1-x)Ge_x(1 0 0) using PH_3 and subsequent Si epitaxial growth by ultraclean low-pressure CVD using Si_2H_6 have been investigated. The quantity of P atoms on Si_(1-x)Ge_x(1 0 0) tends to increase and saturate with temperature, depending on Ge fraction in the range of 200-450℃. By Si epitaxial growth on the P surface at 450℃ using Si_2H_6 instead of SiH_4, heavy P doping with the P concentration over 3 x 10~(21) cm~(-3) is achieved in an ultrathin region at the heterointerface with the thickness within 2 nm. For the P-doped samples, the Hall mobility of the electron is higher than that for uniformly P-doped Si with a lower P concentration of 10~(20) cm~(-3). From the mobility degradation after heat treatment up to 800℃, it is expected that two-dimensional arrangement of P atoms is achieved for the as-deposited films.