Fabrication of discrete gallium nanoislands on the surface of a Si(001) substrate using afocused ion beam

Abstract

A gallium focused ion beam (FIB) has been used to implant Ga at specificsites on the surface of undoped Si(001) substrates. Upon annealing at600 °C, discrete nanoscale surface islands form within the FIB patternedregions when the total Ga ion dose, or fluence, is greater than1.0 × 1016 ions cm − 2. The number of islands depends on the size of the irradiated regionand a single island can be achieved for a FIB milled region that is100 nm × 100 nm.The average sizes of the islands were found to range from 24.5 nm when exposed to a total ion dose of1.2 × 1016 ions cm − 2 to 45 nm fora dose of 3.0 × 1016 ions cm − 2. We have confirmed that these surface islands are metallic Ga by performing aselective chemical etch that removes the islands and by transmission electronmicroscopy characterization. These patterned Ga surface templates could serve asnucleation sites for the lateral arrangement of discrete quantum dot structures.