# Kinetic Monte Carlo simulation of shape transition in strained quantum dots - Condensed Matter > Materials Science

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Abstract: The pyramid-to-dome transition in Ge${x}$Si${1-x}$ on Si100 initiated bystep bunching on pyramidal quantum dots is atomistically simulated using anovel multi-state lattice model incorporating effective surfacereconstructions. Results are explained by a simple theory based on a shallowisland approximation. Under given deposition conditions in $d$ dimensions, theshape transition is shown to occur at island size $n c$ following $n c^{1-d}\propto x^{-\zeta}$ independent of temperature and deposition rate, where$\zeta\alt 2$ and $x$ is the actual Ge concentration in the island. Thetransition has an energy barrier dominated by the facet interface energy. Fastdeposition however can out-run and delay the transition to larger island sizes.

Autor: Chi-Hang Lam

Fuente: https://arxiv.org/