QWIP and MCT for Long Wavelength and Multicolor Focal Plane Array Applications,

Abstract

Abstract : Infrared (IR) sensor technology is critical to all phases of ballistic missile defenses. Traditionally, material systems such as indium antimonide (InSb), platinum silicide (PtSi), mercury cadmium telluride (MCT), and arsenic doped silicon (Si: As) have dominated IR detection. Improvement in surveillance sensors and interceptor seekers requires large size, highly uniform and multicolor (or multispectral) IR focal plane arrays involving mid-wave, long-wave and very-long-wave IR regions. Among the competing technologies are the quantum well infrared photodetectors (QWIP) based on lattice matched GaAs/Al GaAs and strained layer InGaAs/AlGaAs material systems. In this paper, a discussion of cooled IR technology with emphasis on QWIP and MCT will be given. Details will be given concerning device physics, material growth, device fabrication, device performance, and cost effectiveness for long wavelength infrared, very long wavelength infrared, and multicolor applications. The conclusion drawn here is that even though QWIP cannot compete with MCT at the single device level, it has potential advantages over MCT for long wavelength and very long wavelength focal plane array applications in term of the array size, uniformity, operability, yield, reliability, and cost of the systems. QWIPs are especially promising for very-long-wave IR at low temperature operation, and when simultaneous multicolor detection using a single focal plane array is desired. Operating a very-long-wave IR focal plane array at low background is a big challenge to both MCT and QWIP, while QWIP has more potential to be realized due to its good device property at low temperature.