INFRARED FOCAL PLANE ARRAY TECHNOLOGY

Infrared focal plane arrays (IRFPA's) are a critical component needed for advanced infrared imaging systems. Major advances in infrared detectors and microelectronics have led to the development of large area arrays of detectors fabricated using integrated circuit techniques. Requirements for IRFPA's are discussed and an overview is given of different IRFPA architectures. Traditionally, IRFPA's were either hybrid or monolithic architectures, but innovations in epitaxial growth of thin films now allow a number of useful variations. Important IR detector structures are reviewed including photoconductive, photovoltaic, metal-insulator-semiconductor (MIS), and Schottky barrier. Infrared detector materials and related crystal growth techniques are also discussed. In all cases the emphasis is on applicability to IRFPA designs and performance. An important aspect of hybrid arrays is the coupling of the detector to the readout circuitry. This is accomplished through an input circuit-three examples are discussed, namely direct injection, buffered direct injection, and gate modulation. A number of readout techniques have been developed to multiplex the signal and reduce the number of signal leads leaving the array. An overview is given of several readout techniques, including the CCD, MOSFET switch, CID, and CIM. Also discussed are related on-chip signal processing topics as well as questions regarding producibility and array implementation.