Improved Performance of Silicon Carbide Detector Using Double Layer Anti Reflection (AR) Coating

Report No. ARL-TN-0563
Authors: N. C. Das, A. V. Sampath, H. Shen, and M. Wraback
Date/Pages: August 2013; 14 pages
Abstract: Avalanche photodiodes fabricated on a silicon carbide (SiC) substrate showed peak responsivity near 280 nm. The SiC detector structure is grown epitaxially on a 2-μm-thick n-type bottom contact layer followed by a 0.48-μm lightly doped multiplication layer and a top heavily doped 0.45-μm p-type contact layer. Double-layer anti-reflection (AR) coating is grown by a plasma enhanced chemical vapor deposition (PECVD) technique at 250 °C. Using a double-layer AR coating with a bottom silicon nitride (Si3N4) layer and a top silicon dioxide (SiO2) layer broadly enhanced responsivity in the full detector spectral range. We observed that the enhancement of the detector responsivity by using double-layer AR coating is higher than the enhancement observed in a similar device with a single-layer AR coating with a SiO2 film. We observed about 28% increases in detector responsivity by using a double-layer AR coating.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2013