Schottky-barrier focal plane arrays

Abstract

This paper reviews the progress in the development of infrared image sensors with Schottky-barrier detectors (SBDs). Schottky-barrier focal plane arrays (FPAs) are infrared imagers that are fabricated by a well established silicon VLSI process; therefore, at the present time they represent the most advanced technology for large-area high-density focal plane arrays for many SWIR (1 to 3 μm) and MWIR (3 to 5 μm) applications. SBD line sensing arrays with up to 4096 × 4 elements and 2048 × 16 TDI elements were developed, and SBD staring (area) arrays with up to 1040 × 1040 elements have been reported. PtSi SBDs represent the most established SBD technology for applications in the SWIR and MWIR bands. At an operating temperature of 77 K, the dark current density of PtSi SBDs is in the range of 1.0 to 4.0 nÅ/cm2. Pd2Si SBDs were developed for operation with passive cooling at 120 K in the SWIR band. IrSi SBDs have also been investigated to extend the application of Schottky-barrier FPAs into the LWIR (8 to 10 μm) spectral range. Because of very low readout noise, the IR-CCD imagers with PtSi SBDs that have quantum efficiency of 0.5% to 1% at 4.0 μm are capable of 300-K thermal imaging with a noise equivalent temperature (NEΔT) from 0.033 to 0.15 K for operation at 30 frames/s and f/1.0 to f/2.8 optics.