Description: SVT Associates proposes an innovative digital alloy technique to extend the cutoff wavelength of InAsSb beyond 5 um, a wider band gap InAlAsSb layer inserted into depletion region to suppress dark current, and atomic layer deposition technique to coat radiation-hard material AlN on InAsSb detectors grown on GaSb substrate. This digital alloy InAsSb material system is capable of infrared detection between 0.4-5 um, depending on layer thickness of the period of each digital ultra thin superlattice. The goal of this program is to develop InAsSb-based FPA for 0.4-5 um detection at room temperature. Photo detector arrays using this material are of great interest to the NASA for various applications including, in particular, imaging and optical detection, and object discrimination when tracking targets in space or performing astronomical observations. These MWIR photo detectors can also find application to infrared-based chemical identification systems and terrestrial mapping. Applying the dark current suppression and cutoff wavelength extension process to the InAsSb-based detectors should result in higher operating temperature, extended cutoff wavelength, and radiation-hard devices, all important factors that should significantly enhance FPA operation. We intend to characterize the positive effects of proposed techniques in Phase I. In Phase II we will refine the techniques to realize high-performance MWIR FPAs operating at ambient temperatures.

Benefits: Non-NASA Commercial Applications includes pollution monitoring, nondestructive testing, medical diagnostics, spectroscopy, and astronomy.

Commercial applications applicable to NASA include IR imaging arrays for deployment on remote vehicles. The MWIR data is valuable for object discrimination when tracking targets in space or performing astronomical observations. The InAsSb-based FPA developed here operates at room temperature, allowing for the possible replacement of MCT or InSb photodetectors which require more cumbersome cryogenic cooling.