Increase of the electron mobility in HEMT heterostructures with composite spacers containing AlAs nanolayers

The effect of the hybridization of quantum states on electron transport in a two-barrier quantum well $\delta$-doped through a spacer layer at the limit of heavy doping is shown theoretically and experimentally. A method for increasing the electron mobility in the quantum well by suppressing the tunnel coupling with the donor region through the introduction of an AlAs nanobarrier into the spacer layer is proposed. It is experimentally shown that, in the samples with a shallow quantum well, the AlAs nanobarrier introduced into the spacer layer provides a larger than threefold increase in the electron mobility at low temperatures.