Electronic properties of partially relaxed InxGa1-xAs/GaAs multiple quantum well (MQW) structures are investigated using capacitance–voltage (C–V) profiling and deep level transient spectroscopy (DLTS). As the In composition becomes large, the depletion of carriers confined in QWs and the concentration of dislocation-related deep traps are increased. The carrier depletion is observed to occur predominantly in the QWs adjacent to the bottom layer. This depletion is believed to be due to electron capture at the acceptor-like misfit dislocation-related traps. Our results thus show that the C–V and DLTS measurements, combined with the numerical simulation of C–V profiles, can be used to study the influence of nonuniformly distributed misfit dislocations on the carrier distribution in MQW structures. © 1997 American Institute of Physics.