Nanoscale limited area growth of InAs islands on GaAs(001) by molecular beam epitaxy

Growth of InAs islands on a GaAs(001) substrate patterned with similar to50-200-nm diameter holes in an SiO2 mask overlayer providing selective GaAs nucleation areas is reported. The nanoscale pattern was generated in the SiO2 film by large-area interferometric lithography and dry etching. Two-dimensional, 285-nm period, arrays of InAs islands having heights of 10-15 nm with three different bottom diameters of 50-100, similar to150, and similar to200 nm were selectively grown on SiO2 patterned substrates by molecular beam epitaxy. Growth conditions were chosen to provide a very-low sticking coefficient of In atoms on the SiO2 surface suppressing volume contribution from migration of In atoms incident on the SiO2 mask region to nearby open GaAs surface areas. Formation of spherical-section InAs dots with diameters of about 50 nm relying on nanoscale-limited area growth is demonstrated. As the diameter of the hole increases beyond 150 nm, InAs islands deviate from a spherical section and self-assembled quantum dots confined within the open GaAs surface appear. A relation between dot formation and the nanoscale growth area is proposed, with a transition from single- to multiple-dot formation occurring at hole diameters of similar to100-150 nm. (C) 2002 American Institute of Physics.