Quantum box size effect on vertical self-alignment studied using cross-sectional scanning tunneling microscopy

InAs quantum boxes separated by GaAs spacer layers are known to exhibit a vertical self-organization along the growth direction. The alignment probability between two sets of quantum boxes depends strongly on the spacer layer thickness Zs. In this letter, we study samples containing multiple arrays of quantum boxes separated by GaAs spacer layers of various thicknesses, using cross-sectional scanning tunneling microscopy. This work experimentally evidences that the spacer layer characteristic thickness Zs(0) below which a vertical self-alignment occurs, depends on the size of the quantum boxes. These results are interpreted using a theoretical two-dimensional model. (C) 1999 American Institute of Physics. [S0003-6951(99)03618-9].