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Open Access Nano Express

Formation of Ga droplets on patterned GaAs (100) by molecular beam epitaxy

Ming-Yu Li1, Yusuke Hirono2, Sabina D Koukourinkova2, Mao Sui1, Sangmin Song1, Eun-Soo Kim1, Jihoon Lee12* and Gregory J Salamo2

Author Affiliations

1 College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea

2 Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville 72701, AR, USA

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Nanoscale Research Letters 2012, 7:550  doi:10.1186/1556-276X-7-550

Published: 3 October 2012

Abstract

In this paper, the formation of Ga droplets on photo-lithographically patterned GaAs (100) and the control of the size and density of Ga droplets by droplet epitaxy using molecular beam epitaxy are demonstrated. In extension of our previous result from the journal Physical Status Solidi A, volume 209 in 2012, the sharp contrast of the size and density of Ga droplets is clearly observed by high-resolution scanning electron microscope, atomic force microscope, and energy dispersive X-ray spectrometry. Also, additional monolayer (ML) coverage is added to strength the result. The density of droplets is an order of magnitude higher on the trench area (etched area), while the size of droplets is much larger on the strip top area (un-etched area). A systematic variation of ML coverage results in an establishment of the control of size and density of Ga droplets. The cross-sectional line profile analysis and root mean square roughness analysis show that the trench area (etched area) is approximately six times rougher. The atomic surface roughness is suggested to be the main cause of the sharp contrast of the size and density of Ga droplets and is discussed in terms of surface diffusion.