We present data of the interdiffusion coefficient of AlGaAs/GaAs over the temperature range 750–1150 °C, and obtainEAandD0values of3.6±0.2 eVand 0.2 (with an uncertainty from 0.04 to 1.1)cm2/s,respectively. These data are compared with those from the literature taken under a wide range of experimental conditions. We show that despite the range of activation energies quoted in the literature all the data can be described using a single activation energy. Using this value ofEAto fit the published data and then determiningD0for each data point we find that the published data fall into two clusters. One, for samples annealed under a gallium rich overpressure and a second for As rich or capped anneals. This result can be explained by the diffusion in all cases being governed by a single mechanism, vacancy-controlled second-nearest-neighbor hopping. ©1997 American Institute of Physics.