The large-scale assembly of nanowires (NWs) with controlled orientation on surfaces remains one challenge toward their integration into practical devices. A recent paper in Science from the PI’s group reported the guided growth of millimeter-long horizontal NWs with controlled orientations on crystal surfaces. The growth directions and crystallographic orientation of GaN NWs are controlled by their epitaxial relationship with different planes of sapphire, as well as by a graphoepitaxial effect that guides their growth along surface steps and grooves. Despite their interaction with the surface, these horizontally grown NWs have surprisingly few defects, exhibiting optical and electronic properties superior to those of vertically grown NWs. We observed that whereas in a 2D film stress accumulates in two directions, in a NW stress accumulates along its axis, but can relax in the transversal direction, making the 1D system much more tolerant to mismatch than a 2D film. This new 1D nanoscale effect, along with the graphoepitaxial effect, subverts the paradigm not only in the young field of NWs, but also in the established field of epitaxy. This paves the way to highly controlled semiconductor structures with potential applications not available by other means.
The aim of this project is to investigate the guided growth of NWs and unleash its vast possibilities toward the realization of self-integrating nanosystems.
First, we will generalize the guided growth of NWs to a variety of semiconductors and substrates, and produce ordered arrays of NWs with coherently modulated composition and doping.
Second, we will conduct fundamental studies to investigate the correlated structure, growth mechanism, optical and electronic properties of guided NWs.
Third, we will exploit the guided growth of NWs for the production of various functional self-integrating systems, including nanocircuits, LEDs, lasers, photovoltaic cells, photodetectors, photonic and nonlinear optical devices.
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