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Advanced Detectors, Systems, & Nanoscience

High Efficiency Solar-Blind UV III-Nitride Imaging Arrays

Large-bandgap semiconductors such as gallium nitride and its alloys are excellent candidate materials for fabricating solar-blind UV detectors. Previously, we have demonstrated interface-engineered p-i-n GaN detector designs with high quantum efficiency and low leakage. MDL has focused on the development of nitride processing technologies, hybridization schemes, and materials screening infrastructure for the construction of large-format detector arrays. Indium bump reflow processes were developed for the optimization of this hybridization process. An array of rectangular indium bumps is exposed to a hydrogen plasma, and reflowed until the bumps assume a “tent”-like morphology on the underlying readout pads. The wetting between the indium and the under-bump metal-coated bond pad is substantially enhanced by the reflow process.

Above: SEM image of a reflowed indium bump.
 

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