Diffuse omni-directional back reflectors and methods of manufacturing the same

Abstract

Ultra-high reflectivity is projected for internal reflectors comprised of a metal film and nanostructured transparent conductive oxide (TCO) bi-layer on the back side of a semiconductor device. Oblique-angle deposition can be used to fabricate indium tin oxide (ITO) and other TCO optical thin-film coatings with a porous, columnar nanostructure. The resulting low-n dielectric films can then be employed as part of a conductive omni-directional reflector (ODR) structure capable of achieving high internal reflectivity over a broad spectrum of wavelengths and a wide range of angles. In addition, the dimensions and geometry of the nanostructured, low-n TCO films can be adjusted to enable diffuse reflections via Mie scattering. Diffuse ODR structures enhance the performance of light trapping and light guiding structures in photonic devices.

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