Scattering due to spacer layer thickness fluctuation on two dimensional electron gas in AlGaAs/GaAs modulation-doped heterostructures

Abstract

The electron mobility limited by spacer layer thickness fluctuation (SLTF) scattering on the two-dimensional electron gas in AlGaAs/GaAs modulation-doped heterostructure is investigated. Although the SLTF scattering and the interface roughness scattering are both induced by the roughness of the AlGaAs/GaAs interface, they are two different scattering mechanisms. The interface roughness will lead to the fluctuation of the distance from the electrons to the ideal interface and the fluctuation of the spacer layer thickness. The former induces the fluctuation of the electron potential, which works as the interface roughness scattering potential. The latter induces the fluctuation of the sheet carrier density in the channel, which causes a fluctuation in the quantization energy level. The quantization energy level fluctuation works as the SLTF scattering potential. Compared with the interface roughness scattering, the results reveal that the SLTF scattering becomes the dominant scattering mechanism when the doping density in the AlGaAs is high enough.