Kinetic frustration of Ostwald ripening in Ge/Si(100) hut ensembles |
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Authors: | Michael R McKay JA Venables Jeff Drucker |
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Institution: | 1. Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Area della Ricerca di Roma 2 - Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Rome, Italy;2. Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica, 1, 00133 Rome, Italy |
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Abstract: | We show that low area density Ge/Si(100) island ensembles comprised solely of hut and pyramid clusters do not undergo Ostwald ripening during days-long growth temperature anneals. In contrast, a very low density of large, low chemical potential Ge islands reduce the supersaturation causing the huts and pyramids to ripen. By assuming that huts lengthen by adding single {105} planes that grow from apex-to-base, we use a mean-field facet nucleation model to interpret these experimental observations. We find that each newly completed plane replenishes the nucleation site at the hut apex and depletes the Ge supersaturation by a fixed amount. This provides a feedback mechanism that reduces the island growth rate. As long as the supersaturation remains high enough to support nucleation of additional planes on the narrowest hut cluster, Ostwald ripening is suppressed on an experimental time scale. |
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