ESR-Experiments on the Two-Dimensional Electron Gas of Heterostructures
The epitaxial growth of thin layers of semiconductors, where the composition of the material can be changed within one lattice constant, is used for the realization of new microelectronic devices. The simplest structure consists of an interface between the semiconductors GaAs and AlGaAs. Free electrons are present at the GaAs-side of the interface if the AlGaAs material is doped with donors. Calculations show that the electrons are confined within a narrow interface region of about 10 nm which leads to a quantization of the energy within this channel (electric subbands). In our experiments only the lowest electric subband E0 of such a two-dimensional electron gas is occupied with electrons so that the energy is the sum of the fixed energy Eq for the motion perpendicular to the interface and the free motion within the plane.
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