Substrate removal for high quantum efficiency back side illuminated type-ll InAs/GaSb photodetectors

摘要

A substrate removal technique using an InAsSb etch stop layer improves by a factor of 2 the quantum efficiency of back side illuminated type-II InAs/GaSb superlattice photodetectors. After etching of the GaSb substrate with a CrO_3 based solution, the quantum efficiency of the diodes presents Fabry-Perot oscillations averaging at 56%. Due to the confinement of the infrared light inside the devices, the quantum efficiency for certain devices reaches 75% at 8.5 μm. The implementation of this new technique to a focal plane array resulted in a decrease of the integration time from 0.23 to 0.08 ms.