Electron mobility in Si δ-doped GaAs with spatial correlationsin the distribution of charged impurities

We present a theoretical study of electron mobility in heavily Si {δ}-doped GaAs in the presence of applied hydrostatic pressure. At low temperature the electron-ionized impurity scattering is the most important scattering mechanism. The presence of DX centers in Si-doped GaAs results in spatial correlations of the charged impurities, which increase the electron mobility through the structure factor of the charged-impurity distribution and/or a decrease in the density of the charged dopants. A Monte Carlo approach has been developed to simulate this distribution in two dimensions for the d⁺/DX⁰ and d⁺/DX^- models. In the mobility calculation, both intrasubband and intersubband scatterings are considered with the electron-electron screening within the random-phase approximation. A detailed comparison between experiment and theory shows that theory excluding the correlation effects underestimates the electron mobility systematically. In cooperation with other mechanisms, e.g., self-compensation of Si dopants, in the {δ} layer, both DX-center models can explain the experimental results well. This indicates that in order to effectively study the electronic properties of DX centers via the electron mobility in {δ}-doped structures, the samples must have a relatively low doping concentration in order to prevent self-compensation.