Low-temperature electron mobilities due to ionized-impurity scattering in multisubband two-dimensional semiconductor systems

We present a theoretical and experimental study on the low-temperature electron mobilities due to ionized impurity scattering in a multisubband quasi-two-dimensional semiconductor system. The scattering rate is obtained from the solution the Lippmann-Schwinger equation in momentum space and the screening is considered within the random-phase approximation. A quantitative agreement is reached between the theoretical and experimental results for both the quantum and transport mobilities.

Figure 1

The ratio of the scattering rates obtained within the LS equation and the Born approximation for conduction electrons in (a) the first and (b) the second subbands for the $\delta$-doped systems with different densities.

Figure 2

(a) The quantum and (b) the transport mobilities for the first $(n=1)$ and second $(n=2)$ subbands in the $\delta$-doped system. The solid and dashed curves are obtained within the LS equation and the Born approximation, respectively. The experimental mobilities are indicated by the symbols.

Figure 3

The bare (thin curves) and screened (thick curves) impurity potential at the $z=0$ plane in the real space for electrons in the first (solid curves) and the second (dashed curves) subbands. $N_e={10}^{12}{\mathrm{cm}}^{-2},R_y=5.48\mathrm{meV},a_B=99.8\mathrm{\AA },E_{F1}=25.50\mathrm{meV}$, and $E_{F2}=4.18\mathrm{meV}$. The inset shows the Friedel oscillations.