Temperature dependence of electron mobility in GaAs-${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Al}}_{\mathrm{x}}$As modulation-doped quantum wells

We report the temperature dependence of the drift mobility in GaAs-${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As modulation-doped quantum wells. A theoretical model is formulated that includes scattering by residual impurities located in the well, in the barrier, and at the ‘‘inverted’’ interface, by Si donors and acoustic phonons. Contributions to the total mobility arising from the segregated Si profile and background impurities piled up at the inverted interface are separated by secondary-ion mass spectrometry experiments and measurements of the temperature dependence of the scattering rate. The density of scattering centers trapped at the inverted interface increases with alloy composition x, independently of the ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As barrier thickness.