Pylypchuk O. Galvano-magnetic phenomena in the selectively doped heterostructures AlGaAs/GaAs and InGaAs/GaAs.

The transport mechanisms of charge carriers in quantum wells of the selectively doped multi-periodical heterostructures AlGaAs/GaAs/AlGaAs and GaAs/InGaAs/GaAs with stand-alone and tunnel-coupled wells were experimentally investigated. The investigations were carried out within the temperature range from 4 K to 300 K under the equilibrium conditions. Also the carriers were heated by the lateral electric field. We studied the temperature dependences of the Hall effect, conductivity, and the dependence of magnetoresistivity on the magnetic field. It is shown that in the presence of doping impurity in the quantum well the lateral conduction is caused by transport via both quantum-confined subbands and the impurity band. As a result, the electron mobility in the stand-alone quantum wells is small. The mobility increases with the increase of doping impurity concentration. For the double tunnel-coupled wells, the sharp minimum in the temperature dependence of the Hall mobility is observed. The influence of conduction via impurity delta-layers in the AlGaAs/GaAs/AlGaAs structures with the stand-alone quantum wells and delta-doped barriers on the phenomena in magnetic fields was defined. It is found that the value of the low-temperature electron mobility in the impurity wells of such structures is less than in the case of the stand-alone delta-wells. The effect of redistribution of electrons between the regions with different electron mobilities and its influence on the non-linearity of the current-voltage characteristics of tunnel-coupled pairs ("structural well - impurity delta-well" and "structural well - superlattice fragment") were studied.