MERCURY CADMIUM TELLURIDE MATERIAL REQUIREMENTS FOR INFRARED SYSTEMS

High-quality semiconductor material is essential to the production of high performance, affordable semiconductor components. With infrared (IR) components, the maturity and quality of the material has an increased significance, affecting not only component characteristics, but also system performance and cost. The criteria for selection of the focal plane material involves consideration of the system cooling requirements, spectral band, nonuniformity correction, and even system reliability. Each of these system parameters has a direct relationship to the IR material. The system requirements place demands on the quality and cost of the starting material and help to define the appropriate material growth technique, wafer size, the requirements for on-chip signal processing, and relevant material figures-of-merit. A concurrent engineering approach to IR material development is necessary, taking into account both the material limitations and the demands of the infrared imaging system for the proposed application. In addition to the material performance figures-of-merit, the impact of the material on device fabrication and system cost must be taken into account. Ideally, a quantitative assessment of the effect of IR material characteristics on detector module cost and on system complexity should guide this process. Mercury cadmium telluride (MCT) has been the dominant IR material for a broad range of system applications. However, the cost and availability of the MCT are major considerations in the production of affordable IR local plane arrays. This article discusses these general issues relative to the state-of-the-art of this IR material, and provides generic guidelines for the selection of material for IR imaging applications.