Pixel isolation of low dark-current large-format InAs/GaSb superlattice complementary barrier infrared detector focal plane arrays with high fill factor

Low dark current and high fill factor are two crucial characteristics for the realization of the InAs/GaSb superlattice (SL) technology as third generation focal plane arrays (FPAs). Recent development proved high performance results for the complementary barrier infrared detector (CBIRD) design, and a high-quality etch technique is required to minimize surface leakage currents. We report on a n-CBIRD with 10.3 mu m cutoff, exhibiting a responsivity of 1.7 A/W and dark current density of 1x10(-5) A/cm(2) at 77K under 0.2 V bias, without AR coating and without passivation. Results from four different mesa isolation techniques are compared on single element diodes: chemical wet etch using C4H6O6:H3PO4:H2O2:H2O, BCl3/Ar inductively coupled plasma (ICP), CH4/H-2/Ar ICP, and CH4/H-2/BCl3/Cl-2/Ar ICP. The CH4/H-2/BCl3/Cl-2/Ar etched structures yielded more than 2.5 times improvement in dark current density and near-vertical sidewalls. Using this etching technique, we then implement a 1k x 1k p-CBIRD array with 11.5 mu m cutoff and peak responsivity of 3 A/W. Operating at T = 80K, the array yielded a 81% fill factor with 98% operability and performance results of 21% quantum efficiency, 53 mK NE Delta T, and NEI of 6.9x10(13) photons/sec-cm(2).