  To induce a strong Rashba effective magnetic field and enhance its
sensitivity to an external electric field, we propose acceptor doping in
quantum wells. The acceptors are doped at the center of the well, and donors
are doped in the barrier layers to compensate the acceptors and induce
conduction electrons. In strongly doped wells, the electric field on these
conduction electrons is easily changed by a weak external electric field, by
virtue of the strong internal electric field between the acceptors and donors
and the resulting high triangle potential barrier induced in the well. As a
result, the Rashba effective magnetic field, proportional to the electric field
on the electrons, is quite sensitive to the external electric field. Numerical
calculations demonstrate that the sensitivity of the Rashba field is larger by
two orders of magnitude than that in undoped wells.
