Defect Mitigation Processes for III-V-based Infrared Detectors

ABSTRACT:nBn detectors progressed significantly to the point that dual and triple band devices become possible, especially the ability to add Hot-MWIR to multi-color FPA. The main challenge in improving performance of nBn devices is the minority carrier lifetime which influence the reduction of dark currents, increase operation temperature, pixel operability and improve triple color nBn. Improving lifetime is a complicated task in development semiconductors. There is limited number of parameters that can be controlled through growth process (inside MBE) and after growth process which influence the lifetime. However, the real test is devices (FPAs) performance. In this project we will focus on characterization and mitigation of defects in our innovated absorber material for the nBn Hot_MW-LW by using Hydrogenation and/or RTA followed by characterization of dark current and Deep Level Transient Spectroscopy (DLTS) measurements. We successfully measured reduction of dark current for a few hydrogenated and RTA nBn devices in our lab. Our goal in Phase-I is to process 30 nBn Hot_MW-LW at different Hydrogenation and/or RTA conditions, characterize using dark current and DLTS. We expect to improve the process of 1280X1024 12um pitch dual color and triple color FPAs by reducing the dark currents in couple orders of magnitude. BENEFIT:The current MWIR, LWIR and dual band (cool) market is mainly military applications and estimated at $3B for IDCAs annually, with the average IR camera costing more than $100,000. nBn Technologies has relations with Night Vision, NVESD (phase II for hot MWIR camera), MDA (phase-I, 2 color detector and phase-II- LWIR detector) and others. The use of this improved process for our dual and triple band cameras will increase the detector performance. New market includes Homeland security (trough wall imaging), Mine detection, Human body and trough human body imaging, atmospheric imaging and gas detection are only a few examples of new markets for the improves dual and triple bands cameras. nBn Technologies will capture considerable market share via two simple methodologies; superior technology and offering competitive pricing. Superior Technology It is clear that nBn Focal Planes provide excellent imaging characteristics at high operating temperatures. The use of the dual band which operates in the Hot_MW-LW using a micro cooler for the all temperature range (200-100K) is very unique to the nBn. Reduced maintenance and longer service life dual and triple band which include the Hot-MW will significantly reduce maintenance, lowering ownership costs and increasing Yields. This concept of using the HOT-MW as a basic operation at 200K with the ability to cool (when needed) to 100K and acquire the LW images is revolutionary and will result in more robust use, reducing failure points and allowing for service life that is expected to be 200% - 400% longer than current IR cameras. Competitive Pricing While in small numbers the costs of the nBn cameras will be ~$50,000 each. In larger quantities (lots of 100 or greater), we believe we can reduce the price of the cameras to approximately $35,000 each. This considerable price reduction will be achieved by: 1. Improving wafer yields by developing new process to reduce dark currents and to improve multi-wafer MBE growth which will reduce wafer and FPA prices. 2. Acquiring volume discounts on IDCA subsystem prices (>=100 units) The combination of Superior Technology (nBn), wafer yield improvements and volume discounts on IDCAs will lower the overall cost of the IDCA.