Researchers in Prof. Mark Brongersma\'s laboratory have engineered a novel patterning scheme for semiconductor nanowires to increase their photon absorption in thin films for solar cells and photo-detectors. By harnessing “leaky mode resonances” this technology allows thin nanowire rods or beams to absorb many more photons than expected by their size. For scale up the inventors have developed techniques to replace a planar film with an array of easily-fabricated rods that cover a large area. With this approach for a given amount of photon absorption an array structure can be made significantly thinner than a traditional planar structure. This technology opens up tremendous opportunities for the realization of a wide range of high-performance nanowire-based optoelectronic devices including solar cells photodetectors optical modulators and light sources. Stage of Research: The inventors have demonstrated this approach with a series of individual germanium nanowire photodetectors and are currently working on demonstrating the effect in nanowire arrays generated by thin film deposition and photolithography. Applications: 1) Solar cells 2) Photodetectors 3) Optical modulators with end-user applications in data communications
1) Efficient photon management: improved light absorption – up to a factor of 10 for some wires at some wavelengths of light carriers are less likely to encounter traps and defects as they traverse a shorter distance 2) Fast transmission - with thinner films generated carriers must travel a smaller distance and high-speed photodetectors can be made to operate faster 3) Reduced cost because thinner film uses less photo-absorbing material 4) CMOS-compatible fabrication - straightforward lithography and etching techniques can produce wires with square and rectangular cross sections that exhibit similar performance enhancements to circular cross section wires 5) Flexible layout - any solar-cell or photo-detector device layout can be readily modified to work in this new geometry