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.