SE image of focused ion beam created III-V nanospikes

Joanna Millunchick

Focused ion beam (FIB) irradiation and patterning of semiconductors has been demonstrated as a method for the creation of unique nanostructures. The III-V semiconductors in particular show a wide range of responses to FIB irradiation depending on material and exposure conditions. We have characterized the 30 kV normal incidence FIB response of GaAs, InAs, InP, and AlAs. As has been previously observed by other researchers, under normal incidence 30 kV FIB irradiation GaAs, InAs, and InP all form group III rich droplets. However, by varying exposure conditions or by starting with III-V heterostructures other structures may be produced as well. We have found that under certain FIB conditions irradiation of InAs films grown on InP can be used to produce a variety of nanostructures besides group III droplets, including nanoscale semiconductor spikes. These semiconductor spikes form a heterojunction with the substrate, and their location may be controlled and templated. Work is currently underway to characterize the structural, chemical, and electrical properties of these semiconductor nanospikes.