The low-temperature 2D mobility for metallic p-type GaAs Quantum Well

At T $<$ 1.2K the mobility $\mu$(T) is determined by charged trap ionized impurity scattering (iis) and T-dependent screening [1]. $\mu$(T) is calculated with $<$$\tau$(E)$>$ given by an empirical expression $\tau$ = $\tau$$_{o}$x/[x + C tanh($\eta$/2)] [x = E/kT, $\eta$ = T$_{F}$/T and a 2D DOS that features a pseudogap. $\mu$(T) exhibits a minimum at T$_{m}$ = T$_{F}$/2.25 and increases slowly for T $>$ T$_{m}$. The physical reason for this unusual increase in $\mu$(T) is explained. The coefficient C is directly related to $\mu$(0)/$\mu$(T$_{m}$ [4.0 $>$ ratio $>$ 3.6 for p-type GaAs data [2]]. The T-dependent screening $\kappa$$_{2}$(T) = s(T) $\kappa$$_{2}$(0) and s(T) is given by [$\mu$(T)-$\mu$$_{m}$]/ [$\mu$(0)-$\mu$$_{m}$]. This s(T) allows the determination of T* [d$\sigma$/dT = 0] where T* is slightly less than T$_{m}$. The data [2] is an example of ideal 2D behavior. The role of interactions for T $<$ T$_{m}$ and T $>$ T$_{m}$ will be discussed. [1] F. Stern, PRL 44, 1469 (1980); [2] X.P.A. Gao et al., PRL 93, 256402 (2004).