Interference ionization of impurity by electric field in coupled quantum wells

A dramatic modification of the ionization energy of Si donors has been obse rved experimentally in a GaAs/AlGaAs double-well quantum-scale structure, c aused by relocation of the electronic wave function from a delta-doped to a n undoped quantum well in an external electric field. With the bias applied to the structure changing by less than 1 V, the impurity ionization energy falls from 15.5 meV down to zero. The observed anomalously high intensitie s of the photoluminescence transitions involving the first excited electron and heavy-hole subbands are explained by a distortion of the potential rel ief of the structure by the built-in field.