SELF-CONSISTENT CALCULATION OF IONIZED-DONOR DISTRIBUTION IN A NANOSTRUCTURED HETEROJUNCTION WITH CORRUGATED GATE

We calculate self-consistently the spatial distribution of ionized sil icon donors in the barrier of a nanostructured GaAs-AlxGa1-xAs heteros tructure with a corrugated top gate, as well as the electron density o f the corresponding modulated two-dimensional electron gas (2DEG). The geometry of the periodically corrugated Schottky gate gives rise to a n inhomogeneous occupation of deep donor levels (DX centers) at room t emperature, which freezes in when the device is cooled down. This char ge pattern can nearly compensate the desired field effect near the GaA s-AlxGa1-xAs interface. On the other hand, moderate doping of the barr ier is predicted to lead to an improvement of the confinement potentia l, which affects the electrons in the 2DEG. Our numerical treatment of the laterally modulated electron density combines a Fang-Howard varia tional approach describing quantum confinement in the growth direction and a Thomas-Fermi approximation modeling the lateral inhomogeneities , and covers the gate-voltage-induced crossover from a weakly modulate d 2DEG to isolated quantum dots.