TECHNOLOGY AREA(S): Electronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 5.4.c.(8) of the solicitation. OBJECTIVE: Develop short-wavelength infrared focal plane arrays (SWIR FPA) for hyperspectral imaging at an extended cutoff wavelength of 2.5 m and an operating temperature above 200 Kelvin using III-V semiconductor materials. DESCRIPTION: Hyperspectral imaging at full SWIR spectral band (0.9 2.5 m) has important military applications. When used as an imager, a SWIR camera can operate at night using light reflected off the subject in the scene, generating high resolution images with details such as shadows and surface roughness. Compared to thermal infrared imaging, SWIR images look more like visible images and thus scene interpretation is much easier. Even on moonless nights, natural background radiation from the sky, called nightglow, provides useful illumination for imaging. Additional advantages include imaging through glass windows, some types of camouflage, smokes, fires, and haze with less attenuation than visible light. Many objects of military interest, such as explosives and chemicals, disturbed earth, terrain, and vegetation, contain rich and unique spectral features in the SWIR band. A hyperspectral or multispectral imager can fully explore these spectral features in combination with those contained in an image, thus enhancing many critical military applications such as target cueing and identification, mine field detection, and chemical and biological hazard mapping. High performance SWIR focal plane arrays are a critical component inside a hyperspectral imager. Currently, they are mostly made of bulk indium gallium arsenide (InGaAs) semiconductor material, with a nominal cutoff wavelength of 1.7 m. Efforts have been made to extend the cutoff wavelength to 2.5 m by using a high Indium-to-Gallium ratio compound. However, this causes crystal lattice structure mismatch to the indium phosphide (InP) substrate, and therefore leads to detector performance degradation, e.g., orders of magnitude increase in dark current and deterioration in detector array uniformity. Published studies have shown that a III-V Antimony (Sb)-based superlattice can be an excellent infrared sensing material. High-performance mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) superlattice detectors have been demonstrated [1-2]. Furthermore, researchers at several institutions have successfully validated that such superlattice materials can be designed to have extended SWIR cutoff wavelength of 2.35 m and be operated under thermal-electric cooling [3-4]. These early results show great promise of a III-V superlattice as an innovative and viable new material to overcome technical difficulties associated with the bulk InGaAs material, therefore achieving hyperspectral imaging at full SWIR band. The goal of this solicitation is to develop and demonstrate III-V semiconductor detectors and FPAs that are highly sensitive over the full SWIR band with a cutoff wavelength of 2.5 m. The detector performance goal is the following: quantum efficiency larger than 90% with anti-reflection coating, dark current density less than 7 10-8 A/cm2 at an operating temperature 200K or higher, or within 10-times of Rule 07 if measured at other temperatures [5]. In order to leverage the investment by US commercial semiconductor foundries and to achieve detector lifecycle cost reduction, the preferred detector material is III-V semiconductor. The use of large-diameter GaSb substrate is encouraged but not required. Either bulk semiconductor or superlattice can be exploited in designing the detector architecture. However, consideration should be given to this material selection so that additional detector layers can be integrated to create a multi-band (such as SWIR and MWIR) architecture design in the future. Once the detector performance is demonstrated, it is highly desirable to fabricate FPAs and demonstrate the same dark current and quantum efficiency performance on the array level, using an existing in-house or commercially-available read-out integrated circuit (ROIC). The ROIC read noise should be sufficiently low that detector dark current performance can be demonstrated at temperatures controlled with a thermal-electric cooler or a cryogenic cooler with small size, weight, power, and cost. An FPA format 640x480 or larger, and pixel pitch of 15 m or less is preferred. Pixel operability performance goal is greater than 99.9% in both dark current and quantum efficiency. PHASE I: Design a detector as described above. Demonstrate the feasibility of achieving dark current and quantum efficiency performance of 10 times of Rule 07 and 85% respectively. Identify suitable ROICs and collaborators for Phase II FPA demonstration. PHASE II: Fabricate and fully characterize a focal plane array using the detector design from Phase I. This may involve optimization of detector design, detector array processing and hybridization to a suitable ROIC, passivation, and FPA packaging with a thermal-electric or a cryogenic cooler. In-house or commercially available ROICs, either analog or digital, can be used. An FPA format of 640x480 or larger, and pixel pitch of 15 m or less is desired. PHASE III DUAL USE APPLICATIONS: The contractor shall pursue technology transition and commercialization of full-band SWIR hyperspectral imaging technologies developed under this solicitation, potentially having a number of important military, homeland security, agricultural, and industrial applications. These include, but are not limited to, chemical biological hazard detection, soil properties determination, vegetation identification and low moisture stress level monitoring, disturbed earth and terrain analysis, wide-area mapping of distinct mineral deposit concentrations and locations, food processing and sorting, material processing such as semiconductor and solar cell processing, pharmaceutical processing, material recycling such as plastics sorting, vehicle navigation, and machine vision. Particular Army transition paths include Airborne Cueing and Exploitation System Hyperspectral (ACES Hy), Enhanced Medium Altitude Reconnaissance and Surveillance System (EMARSS), and Airborne Reconnaissance Low-Enhanced (ARL-E). REFERENCES: R. Rehm et al., Dual-colour thermal imaging with InAs/GaSb superlattices in mid-wavelength infrared spectral range, ELECTRONICS LETTERS, Vol. 42, No. 10, 11th May, 2006 Klipstein et al, InAs/GaSb Type II superlattice barrier devices with a low dark current and a high-quantum efficiency, SPIE Vol. 9451, paper 94510K, 2015. Noam Cohen et al., Extended wavelength SWIR detectors with reduced dark current, SPIE Defense and Security Conference Paper 9451-102, 2015 Sumotomo SWIR FPA Brochure, SPIE DSS Conference Exhibit at Baltimore, April 2015. W. Tennant, D. Lee, M. Zandian, E. Piquette, M. Carmody, MBE HgCdTe Technology: A Very General Solution to IR Detection, Described by Rule 07'', a Very Convenient Heuristic, J. of Electronic Materials 37, 1406 (2008);SPIE proceedings on Infrared Technology and Applications, 2006-2012. KEYWORDS: Hyperspectral Imager, HSI, Multispectral Imager, SWIR Detector and FPAs with Extended Cutoff Wavelength, III-V Semiconductor Materials, Superlatttice, SWIR/MW Dual-band FPAs, Passive Infrared TPOC-1: Dr. Craig Lennon Phone: 703-704-1318 Email: craig.m.lennon.civ@mail.mil TPOC-2: Dr. Meimei Tidrow Phone: 703-704-2793 Email: meimei.tidrow@us.army.mil
