Anomalously large real space charge transfer through thick barriers in GaAs asymmetric double quantum wells is studied. This inter-well excitonic transfer is very large when the barrier is the Al0.3Ga0.7As alloy, but disappears when the barrier is an equivalent GaAs/AlAs digital alloy. These results combined with observed x and barrier thickness dependence suggest that the inhomogeneities in the barrier may be responsible for this transfer. This picture is supported by the quantum mechanical calculation in three dimensions.
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growth direction . We performed the quantum mechanical calculation for various sizes of rectangles to study the cluster size effect on t. Furthermore, the possible effect of “kinks” was considered( Fig. 4(c)) in connection with  where the GaAs “quantum wires” were shown to “zigzag” their ways through the barrier. In Fig. 4(d), t of holes as a function of x are plotted for several cluster sizes using the model of Fig. 4(b). Holes are consideredb ecausew e assumet hat holes determine the transfer of excitons due to their slower transfer compared with that of electrons. For the grid size of 4 A, the results are only slightly larger than the prediction of the mean field theory, despitet he fact that theree xists many low potential quantum wires in the barrier. The physics of this is the same as described earlier: the pathways are much narrower than the wavelength. Increasing the cluster size-rapidly enhances t, so that for the cluster size of 30A, nearly all holes can pass Acknowledgements-This work was partially supported by Korean Science and Engineering Foundation (951-0205-023-2), Ilju Cultural Foundation, and the Basic Science Research Institute Program of the Ministry of Education (BSRI 94-2421 and 95-E-4009).
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Materials Chemistry