Date of Award

7-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical and Civil Engineering

First Advisor

Bo Yang

Second Advisor

Pei-Feng Hsu

Third Advisor

Muzaffar A. Shaikh

Fourth Advisor

Paavo Sepri

Abstract

Self assembled quantum dots (SAQDs) have drawn great interest recently due to their novel optoelectronic properties. We present an in-depth analytical study of the nucleation and growth of SAQDs on a heteroepitaxial layer. We discuss the fundamental uses of SAQDs on the epitaxial layers. Shape and size distribution of SAQDs greatly affect the functionality of the semiconductor nanostructure. Organized nucleation and growth are most of the times, if not all, desired. Fabrication of organized SAQDs may be fulfilled by using different types of stressors7 which concentrate energy and help in the nucleation of a surface QD. Numerical simulations with a dislocation as stressor are conducted and the results are compared with existing experimental observations. Energetic approach in the particular form of elastic energy release rate (EERR) is utilized to predict the nucleation and growth of SAQDs in the presence of the stressors. Some of the experimental observations are predicted and explained through the simulations. For instance, it is found that a SAQD would gain higher driving force of growth near the surface step corresponding to a dislocation but only on one side of the surface step. It is also predicted that the dislocation would set in a greater bias to the formation of a SAQD when the size of the SAQD is smaller. The present study would be beneficial to our scientific understanding of the physical process and to the technological development of the semiconductor nanostructure.

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