A numerical study of broadband absorbers for visible to infrared detectors

We have studied the electromagnetic response of micro-structured surfaces realized with pillar arrays intended to provide a broadband (0.5-5.0 mu m) absorption enhancement for HgCdTe photovoltaic detector arrays. We have considered both square and hexagonal lattice pillar configurations. Using a finite-difference time-domain approach we have found that the absorption enhancement is weakly dependent on the pillar lattice type, but the lattice period does have a significant impact on the enhancement. The use of these micro-structured surfaces makes it possible to eliminate the need for anti-reflection coatings on the detector back-side while maintaining negligible reflectance over a broad spectral band. (C) 2011 American Institute of Physics. [doi:10.1063/1.3632110]