Site-controlled self-organization of individual InAs quantum dots by scanning tunneling probe-assisted nanolithography

A nanometer-scale site-control technique for individual InAs quantum dots ( QDs) has been developed by using scanning tunneling microscope (STM) -assis ted nanolithography and self-organizing molecular-beam epitaxy. We find tha t nanometer-scale deposits can be created on a GaAs surface by applying vol tage and current pulses between the surface and a tungsten probe of the STM , and that they act as "nanomasks" on which GaAs does not grow directly. Ac cordingly, subsequent thin GaAs growth produces GaAs nanoholes above the de posits. By supplying 1.1 ML InAs on this surface, QDs are self-organized at the hole sites, while hardly any undesirable Stranski-Krastanov QDs are fo rmed in the flat surface region. Using this technique with nanometer precis ion, a QD pair with 45 nm pitch is fabricated. (C) 1999 American Institute of Physics. [S0003-6951(99)03048-X].