The antimonide superlattice infrared detector technology program was established to explore new infrared detector materials and technology. The ultimate goal is to enhance the infrared sensor system capability and meet challenging requirements for many applications. Certain applications require large-format focal plane arrays (FPAs) for a wide field of view. These FPAs must be able to detect infrared signatures at long wavelengths, at low infrared background radiation, and with minimal spatial cross talk. Other applications require medium-format pixel, co-registered, dual-band capability with minimal spectral cross talk. Under the technology program, three leading research groups have focused on device architecture design, high-quality material growth and characterization, detector and detector array processing, hybridization, testing, and modeling. Tremendous progress has been made in the past few years. This is reflected in orders-of-magnitude reduction in detector dark-current density and substantial increase in quantum efficiency, as well as the demonstration of good-quality long-wavelength infrared FPAs.Many technical challenges must be overcome to realize the theoretical promise of superlattice infrared materials. These include further reduction in dark current density, growth of optically thick materials for high quantum efficiency, and elimination of FPA processing-related performance degradation. In addition, challenges in long-term research and development cost, superlattice material availability, FPA chip assembly availability, and industry sustainability are also to be met. A new program was established in 2009 with a scope that is different from the existing technology program. Called Fabrication of Superlattice Infrared FPA (FastFPA), this 4-year program sets its goal to establish U.S. industry capability of producing high-quality superlattice wafers and fabricating advanced FPAs. It uses horizontal integration strategy by leveraging existing III-V industry resources and taking advantage of years of valuable experiences amassed by the HgCdTe FPA industry. By end of the program span, three sets of FPAs will be demonstrated-a small-format long-wave FPA, a large-format long-wave FPA, and a medium-format dual-band FPA at long-wave and mid-wave infrared.
Over the past few years, the Missile Defense Agency Advanced Technology Directorate (MDA/DV) has funded the development of a new III-V infrared (IR) sensor focal plane material: type II strained layer superlattice (SLS). Infrared sensors are crucial to missile defense capabilities for target acquisition, tracking, discrimination, and aim point selection; they serve other military sensing applications as well. Most current infrared military systems use mercury-cadmiumtelluride (HgCdTe), a II-VI semiconductor material, for long-wavelength (LW) (8-12 um) focal plane array (FPA) applications. It is difficult to achieve large-format FPAs in HgCdTe at long wavelengths (LW) due to their low yield. The situation is aggravated by the limitation of the small cadmium-zinc-telluride (CdZnTe) substrates. SLS is the only known IR material that has a theoretical prediction of higher performance than HgCdTe. Over the past three years, SLS technology has progressed significantly, demonstrating experimentally its potential as a strong candidate for future highperformance IR sensor materials. In this paper, we will discuss the most recent progress made in SLS. We will also discuss MDA's new direction for this technology development. The plan is to use a horizontal integration approach instead of adhering to the existing vertical integration model. This new horizontal approach is to increase the number of industrial participants working in SLS and leverage existing III-V semiconductor foundries. Hopefully it will reduce the cost of SLS IR technology development, shared foundry maintenance, and future SLS production.
The Missile Defense Agency's Advanced Technology Office is developing advanced passive electro-optical and infrared sensors for future space-based seekers by exploring new infrared detector materials. A Type II strained layer superlattice, one of the materials under development, has shown great potential for space applications. Theoretical results indicate that strained layer superlattice has the promise to be superior to current infrared sensor materials, such as HgCdTe, quantum well infrared photodetectors, and Si:As. Strained layer superlattice-based infrared detector materials combine the advantages of HgCdTe and quantum well infrared photodetectors. The bandgap of strained layer superlattice can be tuned for strong broadband absorption throughout the short-, mid-, long-, and very long wavelength infrared bands. The electronic band structure can be engineered to suppress Auger recombination noise and reduce the tunneling current. The device structures can be easily stacked for multicolor focal plane arrays. The III-V semiconductor fabrication offers the potential of producing low-defect-density, large-format focal plane arrays with high uniformity and high operability. A current program goal is to extend wavelengths to longer than 14 µm for space applications. This paper discusses the advantages of strained layer superlattice materials and describes efforts to improve the material quality, device design, and device processing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.