Bulk InAsSb Barrier Infrared Detectors with Greater Than 5 um Cutoff

Neil Baril ¹ Alexander Brown ¹ Patrick Maloney ¹ Meimei Tidrow ¹ Amy Liu ² Joel Fastenau ² Dimitri Lubyshev ² Yeuming Qui ² Sumith Bandara ¹

¹Science and Technology Division, U. S. Army Night Vision and Electronic Sensors Directorate
²PA, IQE Inc.

Mid wavelength photodetectors based on bulk InAsxSb(1-x) absorbers with greater than 5um cutoff were incorporated into a unipolar barrier architecture are investigated. The detector structures were grown by MBE utilizing an AlSb buffer layer to transition the lattice constant from that of a GaSb substrate to match bulk InAsxSb(1-x) with 19% antimony. Individual devices were fabricated and tested from a detector structure that included a 4µm thick absorber layer and a 150nm AlSb barrier. The measured dark current density, cutoff wavelength, and quantum efficiency were 3 x 10-5A/cm2, 5.4µm, and 45% at 3.4µm respectively. Arrhenius analysis of the dark current vs. temperature and bias indicates sufficient alignment between the valence band of the InAsxSb(1-x) absorber and AlSb barrier layer to avoid formation of a valence band offset.