Low-temperature electron moЬilities in subbands of dimensional quantization in comЬined-doped GaAs/Al$_x$Ga$_{1-x}$As heterostructures

The Shubnikov-de Haas effect, the quantum Hall effect and the electric transport properties of GaAs/Al$_x$Ga$_{1-x}$As heterojunctions have been studied, in which the Al$_x$Ga$_{1-x}$As layer is homogeneously doped with silicon and the GaAs layer is simultaneously 8-doped with different distances L5{200А<L5<1200А} from the 8-layer of the impurity to the heterojunction. The maximum concentration of 2D-electrons achieved is $1.1\cdot10^{13}$ см$^{-2}$ at $L_{\delta}=600 A$. Measurements have been carried out in the temperature range of 0.4<Т<300К in magnetic fields of up to 35Т bу analyzing the transverse magnetoresistance and the Hall effect, two-dimensional concentrations, transport and quantum mobilities of electrons in subbands of dimensional quantization at low temperatures have been determined. Electron mobilities in scattering on ionized impurities have been calculated for а multi-subband case.