Tuning and monitoring of quantum dot growth by anin situcantilever

Abstract

Self-organization of quantum dots (QDs) on an in situ cantilever setup is investigated using a continuum approach. In this QD growth system, the cantilever has two functions. The first function is as a substrate of QD growth and the second is to tune and detect the morphologies of QDs. We calculate the free energy, consisting of elastic energy, surface energy, island-substrate interaction energy, wetting-layer-substrate interaction energy, and island-island interaction energy, and we analyze their contributions to the total free energy in the QD growth system. Then, we calculate the critical quantity of the deposited material, above which the QD growth system will transfer from the planar film state to the island array state, and the curvature of the cantilever during QD growth. The curvatures of the cantilever are functions of island coverage, island size, facet orientation of island, thickness of the wetting layer, and thickness of the cantilever. It is shown that the in situ cantilever setup can not only tune the morphologies of QDs by properly choosing the thickness of the cantilever but can also monitor the QD growth state with a high sensitivity.