Variation of two‐dimensional electron gas mobility with carrier concentrationnshas been examined for different modulation‐doped heterostructures of AlGaAs/InGaAs/GaAs. It is demonstrated that, depending on the method, electrons are distributed among remote impurity sites and different values of mobility can be achieved for the samensand in the same heterostructure. The origin of this finding is associated with the spatial correlations of remote impurity charges which form dipolelike objects consisting positively charged Si donors and negatively chargedDX−states of the same donor. The effect of correlations causes enhancement of mobility of the order of tens of percent and can explain the appearance of the maximum on a mobility versusnsdependence. ©1995 American Institute of Physics.