Suppression of Ostwald ripening inIn0.5Ga0.5Asquantum dots on a vicinal (100) substrate

Abstract

A comparative study of the morphology of self-assembled ${\mathrm{In}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{As}$ quantum dots grown by atmospheric pressure metal-organic chemical vapor deposition on the exact (100) and 2\ifmmode^\circ\else\textdegree\fi{}-off (100) GaAs substrates as a function of growth interruption time (0--1200 sec) is presented. The dots are randomly distributed on the exact (100) substrate, whereas the dots on the 2\ifmmode^\circ\else\textdegree\fi{}-off (100) substrate are aligned along multiatomic steps. As the interruption time $t$ is increased, the density of dots on the exact (100) substrate decreases and their average volume progressively increases with $\ensuremath{\sim}{t}^{3/4}$ dependence, indicating a regular Ostwald-ripening process. By contrast, the average volume of dots on the 2\ifmmode^\circ\else\textdegree\fi{}-off (100) substrate saturates for interruption times over 200 sec and shows obvious suppression of ripening. In particular, the size of dots on the 2\ifmmode^\circ\else\textdegree\fi{}-off (100) substrate is limited within the atomic terrace width $(\ensuremath{\sim}55\mathrm{nm}).$ These results demonstrate that the density and size of dots could be controlled by interruption time and substrate miscut angle.