EXCHANGE-INDUCED AND CORRELATION-INDUCED CHARGE-TRANSFER OBSERVED IN INDEPENDENTLY CONTACTED TRIPLE-QUANTUM-WELL STRUCTURES

There have been predictions that for closely spaced two-dimensional el ectron gases (2DEG's), charge transfer between the 2DEG's can arise fr om electron interactions due to exchange and correlation [Ruden and Wu , Appl. Phys. Lett. 59, 2165 (1991)]. In this study, we are able to de termine accurately the charge in each of the 2DEG's of a triple-quantu m-well structure. The results demonstrate that as the charge in one 2D EG is reduced, by applying a negative gate voltage the adjacent layer can gain charge; thus charge is effectively transferred between the 2D EG's. This type of charge transfer cannot be explained by a simple non interacting model of the structure, but can be modeled by including in tralayer electron interactions in the form of exchange and correlation correction terms within the local-density approximation. The inclusio n of these many-body interaction terms into our model leads to a good qualitative agreement with the experimental data, confirming that the origin of the charge transfer is electron interactions.