Local intermixing of GaAs/GaAlAs quantum structures by individual ion implant tracks

The intermixing of GaAs/AlGaAs quantum wells due to the passage of single energetic heavy ions (8 MeV Bi) is deduced from photoluminescence measurements after rapid thermal annealing (900°C, 4 min). It is found that while the structural damage radius around an ion track due to pure kinematic mixing is very small (1.0-3.0 nm), thermal annealing increases this mixing radius by more than an order of magnitude (to ∼20 nm). This finding has important implications for ion-beam definition of quantum dots or wires in quantum well structures. Our results also clarify the proposed explanation of particle channeling as the cause of ion induced mixing far in excess of the amorphous range.