256 X 256 Hybrid Schottky Focal Plane Arrays

Abstract

Hughes Aircraft Company has successfully developed and demonstrated MWIR staring focal plane array (FPA) technology using Schottky barrier detectors with arrays consisting of 30 micron pixel spacings in 256 x 256 array format. The hybrid Schottky barrier FPA is a key technology which will permit implementation of a simple, low-cost, single field-of-view IR sensor design. The use of Schottky barrier detectors in FPAs is an outgrowth of earlier work conducted by RADC. A 128 x 128 hybrid Schottky barrier FPA was demonstrated in September 1984, with good detection and recognition performance and image quality against tactical targets. The Schottky barrier 256 x 256 MWIR hybrid focal plane array is a result of an on-going developmental process which has evolved from a 62 x 58 FPA, through a 128 x 128 FPA. Evolution of these arrays has included both improvements in the detector arrays as well as the readout or signal processing structure. The readout has been redesigned to reduce the number of clocks and biases necessary for operation. Reported is the requirement, design, fabrication, and test results of this high density hybrid FPA based upon platinum silicide infrared detector technology. The hybrid approach has advantages of ease of fabrication, high optical fill factor, compatibility with existing multiplexer technology, and excellent imaging performance. We review past Schottky FPA development at Hughes Aircraft and discuss the technical trade-offs of our approach. Discussed is the design, fabrication, and test results of our most recent Schottky FPA.