Electron effective mass and momentum relaxation time in one-sided $\delta$-doped PHEMT AlGaAs/InGaAs/GaAs quantum wells with high electron density

Using the Shubnikov–de Haas effect, the dependences of electron effective mass $m^*$ and transport and quantum momentum relaxation times in Al$_{0.25}$Ga$_{0.75}$As/In$_{0.2}$Ga$_{0.8}$As/GaAs pseudomorphic quantum wells with one-sided silicon $\delta$-doping on the electron density in the range of (1.1–2.6) $\times$ 10$^{12}$ cm$^{-2}$ have been established. Nonparabolicity coefficient $m^*$ in the linear approximation was found to be 0.133 $m_0$/eV. Both the transport and quantum momentum relaxation times depend nonmonotonically on Hall electron density $n_H$, which is related to the competition between growth mechanisms of the Fermi momentum and the increasing contribution of large-angle scattering with increasing donor concentration.