P atomic layer formation on Si1-xGex(1 0 0) using PH3 and subsequent Si epitaxial growth by ultraclean low-pressure CVD using Si2H6 have been investigated. The quantity of P atoms on Si1-xGex(1 0 0) tends to increase and saturate with temperature, depending on Ge fraction in the range of 200-450 °C. By Si epitaxial growth on the P surface at 450 °C using Si2H 6 instead of SiH4, heavy P doping with the P concentration over 3 × 1021 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 1020 cm-3. From the mobility degradation after heat treatment up to 800 °C, it is expected that two-dimensional arrangement of P atoms is achieved for the as-deposited films.
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