Collective excitations in symmetric p-type GaAs/AlxGa1-xAs quantum wells -: art. no. 035314

We present a calculation of the collective plasmon excitations in p-type GaAs/AlxGa1-xAs quantum wells that is based on the random-phase approximation and, within the k .p model takes exactly into account band-structure effects and the strong dependence of the subband wave functions on the in-plane wave vector. For symmetrically modulation-doped wells, the subband structure in the Hartree approximation, plasmon dispersions, single-particle excitations, and energy-loss spectra at zero temperature are consistently calculated. In contrast to the corresponding n-type quantum wells, a multisubband approximation yields a strong coupling of the intra- and intersubband plasmons, even in symmetrical wells, and predicts the existence of an additional intersubband plasmon at finite wave vectors; These drastic differences between electron and hole quantum wells are attributed to the finite overlap between eigenfunctions belonging to different subbands and different in-plane wave vectors, which exists in hole but not in electron systems.