We have shown that doping InGaAs/GaAs quantum well materials with 1019Si/cm3causes a time and temperature dependent diffusion process, which can be correlated with group III vacancy formation. This process can be modeled and shown to accurately fit other data in the literature. Samples with silicon doping concentrations below this value have no enhanced interdiffusion, in contradiction to the results of the Fermi level model. These results are shown to be comparable to data for AlGaAs/GaAs interdiffusion with doping concentrations between 5×1017cm−3and 1018cm−3. We have shown that the position of the Fermi level plays no role in III–V intermixing. ©1997 American Institute of Physics.