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

摘要

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- m-thick n-type bottom contact layer followed by a 0.48- m lightly doped multiplication layer and a top heavily doped 0.45- m 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.