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Bismuth Surfactant Mediated Growth of InAs Quantum Dots by Molecular Beam Epitaxy

Bismuth Surfactant Mediated Growth of InAs Quantum Dots by Molecular Beam Epitaxy. Dongsheng Fan 1,2 , Zhaoquan Zeng 2 , Vitaliy G. Dorogan 2 , Yusuke Hirono 2 , Chen Li 2 , Yuriy I. Mazur 2 ,

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Bismuth Surfactant Mediated Growth of InAs Quantum Dots by Molecular Beam Epitaxy

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  1. Bismuth Surfactant Mediated Growth of InAs Quantum Dots by Molecular Beam Epitaxy Dongsheng Fan1,2, Zhaoquan Zeng2, Vitaliy G. Dorogan2, Yusuke Hirono2, Chen Li2, Yuriy I. Mazur2, ZhimingM. Wang2,4, Shane R. Johnson3, Shui-Qing Yu*,1,2, Gregory J. Salamo21Department of Electrical Engineering, 2Arkansas Institute for Nanoscale Materials Science and Engineering, University of Arkansas, USA, 3School of Electrical, Computer and Energy Engineering, Arizona State University, USA, 4State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, PRC Motivation • Good optical quality and high photoluminescence (PL) efficiency are mostly desired for self-assembled InAs QDs • Lowering the density of InAs QD usually will lead to reduced PL intensity • Bismuth, antimony and other elements have been used to improve the optical quality of InAs QDs by increasing the density of the QDs • We present here Bi can also been used to decrease the density of InAs QD while improving the optical quality Experiment • The InAs QDs were grown on n-type (001) GaAs substrates at 480 °C using a Riber-32P MBE system • At 480 °C, Bi only works as surfactant rather than incorporating into lattice • During the growth interruption afte InAs depostion, Bi atoms desorbed from the surface and In atoms re-distributed • Samples were taken out immediately from MBE chamber after the growth QD density deduction PL efficiency Improvement • Coalescence of InAs QDs has been suppressed significantly • The density of InAs QDs has been reduced by half Excitation dependent Temperature dependent • The improvement of optical quaility is attributed to the effect of Bi surfacant during QDs growth by suprrsessing the coalescence and isolating the growth surface from the backgroud impurity Conclusion • Due to the surfactant effect of Bi during InAs QDs growth, the coalescence of QDs was suppressed and the density of InAs was reduced by half. • The PL efficiency of InAs QDs has been improved. Acknowledgement This work is supported by Arkansas Biosciences Institute and MRSEC Program of NSF Grant (DMR-0520550)

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