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Misfit-Guided Self-Organization of Anticorrelated Ge Quantum Dot Arrays on Si Nanowires
journal contribution
posted on 2012-09-12, 00:00 authored by Soonshin Kwon, Zack C.
Y. Chen, Ji-Hun Kim, Jie XiangMisfit-strain guided growth of periodic quantum dot (QD)
arrays
in planar thin film epitaxy has been a popular nanostructure fabrication
method. Engineering misfit-guided QD growth on a nanoscale substrate
such as the small curvature surface of a nanowire represents a new
approach to self-organized nanostructure preparation. Perhaps more
profoundly, the periodic stress underlying each QD and the resulting
modulation of electro-optical properties inside the nanowire backbone
promise to provide a new platform for novel mechano-electronic, thermoelectronic,
and optoelectronic devices. Herein, we report a first experimental
demonstration of self-organized and self-limited growth of coherent,
periodic Ge QDs on a one-dimensional Si nanowire substrate. Systematic
characterizations reveal several distinctively different modes of
Ge QD ordering on the Si nanowire substrate depending on the core
diameter. In particular, Ge QD arrays on Si nanowires of around 20
nm diameter predominantly exhibit an anticorrelated pattern whose
wavelength agrees with theoretical predictions. The correlated pattern
can be attributed to propagation and correlation of misfit strain
across the diameter of the thin nanowire substrate. The QD array growth
is self-limited as the wavelength of the QDs remains unchanged even
after prolonged Ge deposition. Furthermore, we demonstrate a direct
kinetic transformation from a uniform Ge shell layer to discrete QD
arrays by a postgrowth annealing process.
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Keywords
Ge QDQD array growthSi nanowiresuniform Ge shell layercurvature surfaceSi nanowire substrateanticorrelated patterncore diameterGe depositionnanostructure fabrication methodAnticorrelated Ge Quantum Dot ArraysSystematic characterizationsnanowire backbone promisequantum dotfilm epitaxynanoscale substrateGe QD arraysGe QDspostgrowth annealing processmisfit strainQD arraysoptoelectronic devicesnanowire substrate20 nm diameter
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