Lateral patterning of multilayer InAs/GaAs(001) quantum dot structures by in vacuo focused ion beam

Joanna Millunchick

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joannamm@umich.edu

2014 HH Dow

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A. J Martin, T. W Saucer, G. V Rodriguez, V. Sih, and J. M Millunchick (2012)

NANOTECHNOLOGY, 23(13).

We report on the effects of patterning and layering on multilayerInAs/GaAs(001) quantum dot structures laterally ordered using an invacuo focused ion beam. The patterned hole size and lateral patternspacing affected the quantum dot size and the fidelity of the quantumdots with respect to the lateral patterns. 100\\% pattern fidelity wasretained after six layers of dots for a 9.0 ms focused ion beam dwelltime and 2.0 mu m lateral pattern spacing. Analysis of the change inquantum dot size as a function of pattern spacing provided a means ofestimating the maximum average adatom surface diffusion length to beapproximately 500 nm, and demonstrated the ability to alter the wettinglayer thickness via pattern spacing. Increasing the number of layersfrom six to 26 resulted in mound formation, which destroyed the patternfidelity at close pattern spacings and led to a bimodal quantum dot sizedistribution as measured by atomic force microscopy. The bimodal sizedistribution also affected the optical properties of the dots, causing asplit quantum dot photoluminescence peak where the separation betweenthe split peaks increased with increasing pattern spacing.

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