LATERAL SPREADING OF FOCUSED ION-BEAM-INDUCED DAMAGE

We study the lateral spreading of implantation-induced damage and measure the position dependence of the cathodoluminescence intensity of GaAs/AlAs heterostructures patterned by a focused Ga+ ion beam. Two luminescence lines, one from a buried AlGaAs/GaAs quantum well and the other from a deeper lying AlAs/GaAs short period superlattice are detected. Implantation doses in the range 10(12)-10(15) cm-2 are investigated. We find that the lateral spreading of implantation induced damage considerably exceeds the implanted region in the case of the quantum well (50 nm below the surface), but is well limited to the implanted region in the case of the superlattice (250 nm below the surface). Micro-Raman measurements allow us to locally probe the degree of crystallinity at a certain point of the sample.