Facilitating growth of InAs-InP core-shell nanowires through the introduction of Al

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• 作者：C.M. Haapamaki^a ; J. Baugh^b ; ^c ; R.R. LaPierre^a ; ^{lapierr@mcmaster.ca}
• 关键词：A3. Molecular beam epitaxy ; B2. Semiconducting III&ndash ; V materials ; B2. Semiconducting aluminium compounds ; B2. Semiconducting ternary compounds
• 刊名：Journal of Crystal Growth
• 出版年：2012
• 期刊代码：49_00220248
• 类别：ch
• 出版时间：15 April, 2012
• 卷：345
• 期：1
• 页码：11-15
• 文件大小：628 K

摘要

InAs nanowires were grown on GaAs substrates by the Au-assisted vapour-liquid-solid (VLS) method in a gas source molecular beam epitaxy (GSMBE) system. Passivation of the InAs nanowires using InP shells proved difficult due to the tendency for the formation of axial rather than core-shell structures. To circumvent this issue, Al_xIn_1鈭?em>xAs or Al_xIn_1鈭?em>xP shells with nominal Al composition fraction of x=0.20, 0.36, or 0.53 were grown by direct vapour-solid deposition on the sidewalls of the InAs nanowires. Characterisation by transmission electron microscopy revealed that the addition of Al in the shell resulted in a remarkable transition from the VLS to the vapour-solid growth mode with uniform shell thickness along the nanowire length. Possible mechanisms for this transition include reduced adatom diffusion, a phase change of the Au seed particle, and surfactant effects. The InAs-AlInP core-shell nanowires exhibited misfit dislocations, while the InAs-AlInAs nanowires with lower strain appeared to be free of dislocations.