Temperature coefficients of low-field electron mobility in GaAs/AlGaAs heterostructures

The temperature coefficients of 2-dimensional electron mobility have been extensively investigated on 7 different GaAs/AlGaAs heterostructures and an additional GaAs:Si thin film. As the temperature decreases from 400 K to 4 K, the high-mobility samples (⩾60 Å) show monotonical increase in electron mobility over the entire range, but the low-mobility samples ( <60 Å) have peaks ranging in 50-100 K and positive temperature slopes below the peaks. The temperature dependences satisfy the linear relation in reciprocal mobility due to acoustic phonons, 1/μ =1/μ_AC(0)+ α T (α > 0), for the high-mobility samples in the range, but the parabolic contribution (1/μ =l/μ_RD(0)+ β T², β <0) which may be attributed to remote donors appears in the low-mobility samples. From the T^-k-dependence in the optical phonon scattering regime, we have obtained an empirical expression as k=k₀+k₁log[ μ (4.2K)/μ (300K)] (k₀=1.0, k₁=0.7), which can be extended to bulk GaAs:Si sample with the mobility ratio much smaller than unity.