2018年7月24日星期二

Selective area growth of III–V nanowires and their heterostructures on silicon in a nanotube template: towards monolithic integration of nano-devices

We demonstrate a catalyst-free growth technique to directly integrate III–V semiconducting nanowires on silicon using selective area epitaxy within a nanotube template. The nanotube template is selectively filled by homo- as well as heteroepitaxial growth of nanowires with the morphology entirely defined by the template geometry. To demonstrate the method single-crystalline InAs wires on Si as well as InAs–InSb axial heterostructure nanowires are grown within the template. The achieved heterointerface is very sharp and confined within 5–6 atomic planes which constitutes a primary advantage of this technique. Compared to metal-catalyzed or self-catalyzed nanowire growth processes, the nanotube template approach does not suffer from the often observed intermixing of (hetero-) interfaces and non-intentional core–shell formation. The sequential deposition of different material layers within a nanotube template can therefore serve as a general monolithic integration path for III–V based electronic and optoelectronic devices on silicon.

Source:IOPscience

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2018年7月1日星期日

Ag-catalyzed InAs nanowires grown on transferable graphite flakes

Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy.


Source:IOPscience

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