STM probe-assisted site-control of self-organized InAs quantum dots on GaAs surfaces

A site-control technique for individual InAs quantum dots (QDs) has been de veloped by using scanning tunneling microscope (STM) probe-assisted nanolit hography and self-organizing molecular-beam epitaxy. We find that nano-scal e deposits can be created on a GaAs surface by applying voltage and current pulses between the surface and a tungsten tip of the STM, and that they ac t as "nano-masks" on which GaAs does not grow directly. Accordingly, subseq uent thin GaAs growth produces GaAs nano-holes above the deposits. When InA s is supplied on this surface, QDs are self-organized at the hole sites, wh ile hardly any undesirable Stranski-Krastanov QDs are formed in the flat su rface region. Using this technique with nanometer precision, a QD pair with 45-nm pitch is successfully fabricated.