Nanoscale selective-area GaAs growth by nitrogen surface passivation and STM surface modification

A new selective-area GaAs growth technique on a nanometer scale is demonstrated by a combination of 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 grown on the surfaces using trimethylgallium and tertiarybutylarsenic. An array of uniform 6-nm-high and 50 × 50-nm² dots was formed on the STM-modified areas. The advantages of the technique are that size-controlled nanostructures can be fabricated in specific positions and that the nanostructures formed are free from contamination because all processes are performed in a vacuum.