"Infrared Image Sensors With Schottky-Barrier Detectors"

Abstract

This paper reviews the progress in the development of infrared image sensors with Schottky-barrier detectors. Schottky-barrier focal plane arrays (FPAs) are the only infrared imagers that are fabricated by the well established silicon VLSI process. Therefore, at the present time they represent the most mature technology for large-area high-density focal plane arrays for many SWIR (1 to 3 μm) and MWIR (3 to 5 μm) applications. Infrared line sensing arrays with up to 4096 x 4 elements and area sensing arrays with up to 512 x 512 elements have been reported. PtSi Schottky-barrier detectors (SBDs) represent the most established SBD technology for applications in the SWIR and MWIR bands at an operating temperature of about 80K. These SBDs can be designed for operation at 77K with a dark current density in the range of 1.0 to 20 nA/cm2. Pd2Si SBDs were developed for operation with passive cooling at 120K in the SWIR band. IrSi SBDs have also been investigated to extend the application of Schottky-barrier focal plane arrays (FPAs) into the LWIR (8 to 10 μm) spectral range. Because of very low readout noise, the IR-CCD imagers with PtSi SBDs which have quantum efficiency of .5 to 1% at 4.0 gm are capable of 300K thermal imaging with a noise equivalent temperature (NEAT) of less than 0.1K for operation at 30 frames/s and f/1.5 to f/3.0 optics.