ABSTRACT
We synthesised and investigated new high-carrier-density GaAs/GaAlAs heterostructures with combined doping, that is with delta-doping by Si of GaAs and uniform doping by Si of GaAlAs layers. The Hall effect and magnetoresistance were investigated for the structures with distances Lg between heterojunction and delta-layer from 200Å to 1200Å. The enhanced 2D electron concentration achieved was 1.1*10−13 cm−2 in six filled subbands for the sample with Lδ=750 Å. Electron mobilities and concentrations in each 2D subband have been extracted from the magnetoresistance and Hall effect data. The electron mobility due to the scattering from ionized impurities has been calculated in the case when several subband are occupied.
