(a) Hall coefficient RH(T) and Hall mobility μH(T), defined as |RH(T)|/ρ(T). The dashed line indicates an approximate T7 dependence of μH(T). The hatchings indicate the regions where multiband effects are present. The one at around 30 K involves two electron-like bands and the one below 7 K is complex and beyond the scope of this work. (b) Electrical resistivity ρ(T) and magnetoresistance MR(T)=[ρB(T)−ρ0]/ρ0. The latter quantity was measured in a magnetic field B=8 T. Three different regions (I, II and III) are indicated, of which region I is characterized by high mobility, intrinsic or deeper donor-derived conductance and region III by low-mobility variable range hopping. The dashed line on top of the ρ(T) curve represents a fit by the thermal activation law. (c) Electrical resistivity plotted as log ρ versus T−1/4. A linear dependence, as well as the negative MR(T ) below about 15 K is characteristic of VRH conduction. VRH, variable range hopping.