Maximum low-temperature mobility of two-dimensional electrons in heterojunctions with a thick spacer layer

Abstract

The calculation of the mobility of the two-dimensional electron gas limited by the remote ion scattering is presented which takes into account the correlation in the spatial distribution of the charged impurities caused by the Coulomb interaction. The correlation function of the charge is characterized by the freezing temperature ${\mathit{T}}_0$. The low-temperature distribution of the charge is supposed to be a snapshot of the equilibrium distribution corresponding to this temperature. At low enough ${\mathit{T}}_0$ this distribution corresponds to the ground state of the system consisting of the charged and neutral impurities. The effect of the correlation is shown to be very essential at low ${\mathit{T}}_0$ and at large spacer thickness. The numerical calculations are performed for modulation-doped ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterostructures. Input parameters are as follows: spacer width (s), temperature (${\mathit{T}}_0$), density of the channel electrons (${\mathit{N}}_{\mathit{s}}$), and density of the charge in the depletion layer (${\mathit{N}}_{\mathrm{depl}}$).