Self-assembling of strain-induced Y2O3 nanostructures grown on LaAlO3 by photo-assisted MOCVD

Abstract

Y2O3 nanodots were fabricated on vicinal substrate (100)-oriented LaAlO3 (LAO) by photo-assisted metalorganic chemical vapor deposition (PhA-MOCVD). Nucleation and growth processes of Y2O3 nanodots self-assembled as rows along the terraces of LAO were investigated with various growth parameters. It is found that density and size of Y2O3 nanodots can be tuned and well controlled by varying substrate temperature (Ts), oxygen partial pressure and growth time. At lower Ts, the morphologies of Y2O3 nanodots are characterized by small and dense solid cones. With elevating Ts, the dots gradually grow larger and sparser. This phenomenon could be illustrated by two competitive kinetic processes, i.e. surface diffusion of adatoms and yttrium desorption. Morphologies of these nanodots were also influenced by variation of oxygen partial pressure. To further discuss the growth kinetics, a more clearly quasi-linear distribution was obtained and the coarsening effect is modified by varying growth time.