Feb 12, 2009
Catalyst-free nanowire axial heterostructures
Until recently, nanowire growth was enabled and controlled by gold nanoparticles, which acted as a growth catalyst. Gold is a banished metal in the semiconductor industry, because it reduces the performance of semiconductors and related devices. Catalyst-free synthesis of nanowires opens the way for future industrial applications. Catalyst-free fabrication of axial heterostructures ensures the necessary design freedom for this to become reality.
Scientists have succeeded in the fabrication of axial heterostructures on catalyst free III-V nanowires. The growth of the wires is achieved from gallium/indium alloy droplets that are nucleated in situ. By variation of the In/Ga beam flux during the growth it was possible to vary the effective indium content up to x = 5%, as deduced from photoluminescence measurements. The heterostructures grown with the method presented were spatially mapped along the wires with confocal microphotoluminescence and cathodoluminescence. It was found as expected that the emission of GaAs/InxGa1−xAs/GaAs heterostructures is localized.
This work was the result of a collaboration between Ecole Polytechnique Federale de Lausanne (EPFL), the University of Lund, University of Barcelona and the Technical University of Munich.
The researchers presented their work in Nanotechnology.
About the author
Anna Fontcuberta i Morral studied physics at the University of Barcelona. She obtained her PhD degree in Materials Science in 2001 at the Ecole Polytechnique in France and then spent two years at the California Institute of Technology as a postdoctoral fellow. After starting her ''nanowire'' research as a CNRS fellow in Ecole Polytechnique, she moved to the Walter Schottky Institute to begin her work on catalystfree III–V MBE grown nanowires. She is currently assistant professor at Ecole Polytechnique Federale de Lausanne. She is also co-founder of the start-up company Aonex Technologies.