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Proceedings Paper

Producible high performace LWIR pv HgGdTe staring focal plane arrays
Author(s): D. J. Gulbransen
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Paper Abstract

In the last two years, Hughes Aircraft Company and the Santa Barbara Research Center have demonstrated that LWIR PV HgCdTe staring focal plane arrays can be fabricated reproducibly with high performance and high yield. Record yields for detectors and readouts, in excess of 50%, have been achieved on 128 x 128 arrays with 40 x 40 gm pixels on 40 jam centers. Key to the successes are the development of p-on-n PV HgCdTe detector technology and high density CMOS readout circuitry. In 1988, Hughes Missile Systems Group established an inventory account whose goal was to fabricate 128 x 128 LWIR FPAs for a broad range of missile requirements. They range from high background tactical applications to low background SDI scenarios. The staring FPA chosen couples a high impedance p-on-n LWIR PV HgCdTe detector array to a CMOS high capacity direct injection readout array and is designated the DI-128. The detector arrays were fabricated with cutoff wavelengths ranging from 9.2 to 9.9 gm and with RoAo products ranging from 100 to 1000 S2-cm2. The excellent RoAo products allow a simple direct injection input circuit to be used while maintaining injection efficiencies in excess of 80% allowing near BLIP performance. The DI input circuit has a charge handling capacity in excess of 20 million carriers. A variable integration time capability is provided for dynamic range management and performance optimization. 39 LWIR HgCdTe FPAs have been fabricated by the inventory account to date with a yield of nearly 50 %. The arrays were tested at 77 Kelvin with an f/2.0 aperture at 295 Kelvin in the 8.0-9.0 gm spectral band resulting in a background flux of 6.0 x 1015 photons/cm2-sec. The array average NEAT achieved was typically in the range 0.025 to 0.020 Kelvin. Excellent dc and ac uniformities of 4-6% were universally observed. The yielded FPAs all had greater than 98.5% operability with many parts achieving greater than 99.5%. Additional tests were performed to determine if the LWIR detectors could be used in the MWIR. The NEAT achieved in these tests was approximately 0.025 Kelvin. the outstanding detector RoAo products achieved at SF RC reduce the leakage current sufficiently to achieve this performance level in the MWIR. The excellent MWIR performance opens the possibility of simultaneous MWIR and LWIR imagery using a single LWIR staring FPA.

Paper Details

Date Published: 29 January 1992
PDF: 16 pages
Proc. SPIE 2075, Passive Sensors, 207509 (29 January 1992); doi: 10.1117/12.2300237
Show Author Affiliations
D. J. Gulbransen, Hughes Aircraft Co. (United States)

Published in SPIE Proceedings Vol. 2075:
Passive Sensors
Joseph S. Accetta; M. J. Cantella, Editor(s)

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