A new approach for reduction of scattering rate of electrons by polar optical phonons in the double barrier heterojunction quantum well is proposed. This approach is based on the phonon localization in narrow phonon wells. The enhancement of the electron saturated drift velocity in the Al_{0.2}Ga_{0.8}As/GaAs/Al_{0.2}Ga_{0.8}As high electron mobility transistor channel is envisaged theoretically and observed experimentally. The drift velocity in the channel in high electric fields (E >10 kV/cm) exceeded the maximal drift velocity in bulk GaAs (v_{max}=10^7 cm/s) and achieved the value of 4×10^7 cm/s.
The following peculiarities of electron transport in In_{0.53}Ga_{0.47}As/In_{0.52}Al_{0.48}As quantum wells with δ-Si-doped In_{0.52}Al_{0.48}As barriers at high electric fields are discovered: (1) an enhancement of electron mobility by inserting the InAs phonon wall into the In_{0.53}Ga_{0.47}As/In_{0.52}Al_{0.48}As quantum well, as well as increasing the InAs content in the modulation-doped In_{0.8}Ga_{0.2}As/In_{0.7}Al_{0.3}As heterostructure; (2) a large decrease in electron mobility and a change of electron density with increasing electric field in the range of 1-4 kV/cm; (3) a magnetic field dependence of the threshold electric field for intervalley scattering of electrons; and (4) microwave current oscillations in high electric fields.
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