Enhancement of the electronic confinement improves the mobility in p-n-p delta-doped quantum wells in Si

The electronic structure and mobility trends in a n-type delta-doped quantum well in Si, matched between p-type delta-doped barriers of the same material, is presented. The distance between the n-type well and p-type barriers is varied from 50 Å to 500 Å; and also the impurity density from 5 × 1012 cm-2 to 5 × 1013 cm -2, for both, donors and acceptors. An increase in the mobility by a factor of 1.6 at interwell distance of 50 Å with donor and acceptor concentrations of 5 × 1012 cm-2 and 5 × 1013 cm-2 compared with a single delta-doped well without p-type barriers is found. This improvement in mobility could be attributed to a better confinement of carriers, which favors excited levels with nodes in the donor plane. This trade-off between carrier concentration and mobility could be exploited in high-speed, high-power and high-frequency applications.

Electronic structure; Silicon; Delta-doped; Donor and acceptor; Electronic confinement; Excited levels; High-frequency applications; Impurity density; P-type; Semiconductor quantum wells

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