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Thermodynamic Self-Limiting Growth of Heteroepitaxial Islands Induced by Nonlinear Elastic Effect—New Progress Made by FIST of XJTU
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    Heteroepitaxially grown self-assembled 3D islands have drawn continued attention due to fundamental interest in understanding their complex growth behavior and their potential applications as quantum dots in nano-electronic and opto-electronic devices. Despite extensive experimental and theoretical studies, however, fundamental understanding of nucleation and growth of strained islands, especially islands with large facet angle on patterned substrates with large inclination angle is far from complete. To get a comprehensive understanding of nucleation and growth mechanism of strained islands on patterned substrate, Dr Hu's group in Material Physics Center(MPC) of Frontier Institute of Science and Technology(FIST) developed a new theoretical model by extending the previous linear elastic approach to nonlinear elastic approach. They found that the nonlinear elastic effect(NLEF) induces a thermodynamic self-limiting growth mechanism that hinders the strain relaxation of coherent island beyond a maximum size, which is in contrast to indefinite strain relaxation with increasing island size in the linear elastic regime. The self-limiting growth effect shows a strong dependence on the island facet angle, which applies also to islands inside pits patterned in a substrate surface with an additional dependence on the pit inclination angle. Consequently, primary islands nucleate and grow first in the pits and then secondary islands nucleate at the rim around the pits after the primary islands reach the self-limited maximum size. The theory sheds new lights on understanding the heteroepitaxial island growth, explains a number of past and recent experimental observations and provides guidance for controlling the growth of heteroepitaxial nanostructures.

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