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Research Activities > Programs > Nonequilibrium Interface and Surface Dynamics 2007

Asymmetric transition states in quantum dots

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Asymmetric transition states in quantum dots

Professor Brian Spencer

University of Buffalo

Abstract:   We present a simple model for the shape transitions of facetted quantum dots in strained solid films. In the absence of substrate miscut, it is known that a truncated pyramid minimizes the energy at small volume while a dome minimizes the energy at larger volume. Here we demonstrate the existence of an asymmetric "half-dome" shape which acts as a low-barrier metastable transition state in the transition from the truncated pyramid to dome. Thus, in a system with moderate fluctuations, half-dome quantum dots should be observed, if only rarely. We also consider the role of substrate miscut on the energetics of quantum dot shape transitions. In the presence of miscut, "half-pyramid" and "half-dome" states play not only the role as intermediaries in the transitions between truncated pyramid and dome, but can even be stable equilibrium states.

This work is in collaboration with Jerry Tersoff.

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