Growth, structural and optical properties of GaN/AlN and GaN/GaInN nanowire heterostructures

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• 作者：B. Daudin^a ; ^{bruno.daudin@cea.fr} ; C. Bougerol^a ; D. Camacho^b ; A. Cros^c ; B. Gayral^a ; K. Hestroffer^a ; C. Leclere^d ; R. Mata^c ; Y.M. Niquet^b ; H. Renevier^d ; D. Sam-Giao^a ; G. Tourbot^a ; ^e
• 关键词：III nitride wide gap semiconductors ; nanowires ; molecular beam epitaxy ; Raman spectroscopy ; Xrays diffraction ; high resolution electron microscopy ; photoluminescence
• 刊名：Physics Procedia
• 出版年：2012
• 期刊代码：P128_18753892
• 类别：ph
• 出版时间：2012
• 卷：28
• 期：Complete
• 页码：5-16
• 文件大小：1909 K

摘要

After discussing the GaN NW nucleation issue, we will present the structural properties of axial and radial (i.e. core/shell) GaN/AlN NW heterostructures and adress the issue of critical thickness during the growth of such heterostructures. Next, we will present the growth of InGaN NWs on a GaN NW base. It will be shown that the morphology and structural properties of the InGaN NW sections depend on the In content: for high In content a flat top is observed and plastic relaxation is occuring, with mismatch dislocations formed at the InGaN/GaN interface. By contrast, for In content below 25%InGaN NWs exhibit a pencil-like shape assigned to a purely elastic strain relaxation process, without formation of dislocations. Such a strain relaxation process was found to be associated with the spontaneous formation of an InGaN/GaN core-shell heterostructure. As concerns optical properties, it will be shown that the purely elastic relaxation process is associated with a marked In clustering. As a consequence, for samples with a 17%nominal In content, data were found to exhibit a S-shape characteristic of localization, with a minimum around 110K. By contrast, for a 40%In content PL data suggest that localization is much weaker. Finally, a growth model of InGaN/GaN heterostructures will be proposed.