Selective-area GaAs growth using nitrogen passivation and scanning-tunneling-microscopy modification on a nanometer scale

A technique for the selective-area growth of GaAs on a nanometer scale is described. The technique comprises nitrogen (N)-passivation mask formation, scanning-tunneling-microscopy (STM) pattern modification, and metalorganic molecular-beam epitaxy. GaAs (001) surfaces are passivated with N radicals dissociated from N₂ molecules and are modified by STM on a nanometer scale. GaAs nanostructures are then grown on the modified areas using trimethylgallium and tertiarybutylarsine. Uniform 6-nm-high and 50×50-nm² dots were formed on 50×50-nm² STM-modified areas. The advantage of the technique is that size-controlled nanostructures can be fabricated in specific positions and these nanostructures are free from contamination because all processes are performed in a vacuum.