Electrical properties of W delta doped Si epitaxial films grown on Si(1Â 0Â 0) by ultraclean low-pressure chemical vapor deposition

Electrical properties of W delta doped Si epitaxial films grown on Si(1 0 0) by ultraclean low-pressure chemical vapor deposition were investigated. In the temperature range of 290-130 K, it is found that the W atoms in Si act as donor, and the sheet carrier concentration is proportional to the W amount. Moreover, the ionization energy is estimated to be about 340 meV on the assumption without the acceptor compensation and is scarcely affected by change of the W amount. Therefore, it is suggested that formation of the donor level is independent of degradation of crystallinity. Slope of the temperature dependence of Hall mobility was much larger than that of the uniformly donor doped Si.