We have studied aluminum‐implantation enhanced intermixing of GaAs‐AlGaAs quantum‐well structures using low‐temperature photoluminescence. The energy shift of the heavy‐hole exciton was determined for Al doses varying from 2×1013cm−2to 1×1015cm−2after either furnace annealing at 800 °C or optical rapid thermal annealing at 925 °C. A variational calculation yields the diffusion length from the energy shift of the exciton. This shift is due both to the increase of Al in the center of the well and to the change in electron and heavy‐hole confinement energies. The ion‐implantation enhancement of the diffusion length depends on Al‐ion dose but not significantly on annealing time or temperature. This work indicates that Al‐ion implantation should be useful for the fabrication of structures of reduced dimensionality by patterned implantation of AlGaAs‐GaAs quantum wells.