Calculation of hole subbands at the GaAs-AlxGa1−xAsinterface

The hole subbands in the inversion layer at the GaAs-${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ interface are calculated self-consistently in the Hartree approximation taking the degenerate structure of the valence band and the matching of the wave functions at the interface into account. The subbands versus the wave vector parallel to the interface are shown to be strongly nonparabolic and spin split. Only the highest subband pair has filled levels and about 64% of the charge is found to be in the uppermost of these spin subbands, in good agreement with experiment. The calculated effective masses are smaller than those found in cyclotron resonance experiments.