TECHNIQUES TO IMPROVE THE QUANTUM EFFICIENCY OF LWIR SLS FPAs

Antimony-based type-II strained layer superlattice focal plane arrays (SLS FPAs) now achieve maximum quantum efficiencies (QE) in the longwave infrared (LWIR) of 50% (cutoff ~ 10-11 microns) and 40% (cutoff ~ 12-13 microns) in commercial production. With a couple changes to the material design, we think we can increase these QE numbers to 70% and 60%, respectively. Our optimism is based on our prior design attempts to increase the QE, combined with observation of material growth effects on QE. In Phase I, we will demonstrate a FPA with improved QE using SLS material that combines these techniques. In Phase II, we will optimize material design, maximize QE, and deliver a camera with a SLS FPA with the highest possible QE. Increasing the QE of FPAs will increase imaging sensitivity and detection range and benefit applications as diverse as infrared astronomy, missile detection and tracking, and imaging very small gas leaks.