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A low-cost method of fabricating large photonic crystal arrays of hexagonal posts without the use of lithography is described, along with an application of enhancing light extraction efficiency in semiconductor light-emitting diodes (LEDs). Polystyrene spheres are deposited onto a wafer surface and then processed to achieve control over photonic crystal lattice properties in a method suitable for fast and repeatable patterning. The spheres serve as an etch mask to extend the photonic crystal formed into the semiconductor surface. This technique is applied to LEDs to increase the top surface light extraction, and 51% wall plug enhancement is demonstrated in deep junction liquid phase epitaxially grown LEDs with absorbing substrates, though is adaptable to any substrate and photonic crystal dimensions.
Date of Publication: Jan.1, 2008