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USNO and NOAO Develop a 1024 x 1024 InSb Device (1Dec93) (from NOAO Highlights!, NOAO Newsletter No. 36, 1 December 1993) Indium Antimonide detector technology has progressed very rapidly in the past few years. In 1987 the 58 x 62 arrays were introduced at NOAO, revolutionizing the IR program. This year the instruments have been upgraded to 256 x 256 InSb. And now we are excited to report that a collaboration is underway between USNO and NOAO to develop a low background 1024 x 1024 Focal Plane Array, called Aladdin. The Preliminary Design Review on the readout design was held with SBRC in October, and the layout and simulations have begun. One of the more difficult problems was getting the device pin count down to 124 pins. The package is a special design and is 1.65 inches square. The performance requirements are shown in the table below and are substantially unchanged from what was reported at the U. of California, Los Angeles meeting on "Astrophysics with IR Arrays" last July. The logic control will be by CMOS shift register and the unit cell will be in PMOS. Both NMOS and PMOS output drivers will be provided and a decision as to which one to use in the hybrids will be made after bare readout testing. A number of features have been incorporated in this design to reduce the clocking feedthrough to the detector node. This has been a problem with the existing 256 x 256 InSb FPA, and it has a drastic effect on full well capacity. The architecture is four completely electrically-independent quadrants (hence the large lead count) but the detector pitch will be continuous so that no loss of fill factor will be experienced at the quadrant seams. [Figure not included] This figure shows the impact of the increasing format size for imaging the Galactic center, the three panels illustrating a single frame at 58 x 62, 256 x 256, and 1024 x 1024 pixels respectively. We are in the process of setting up a notice and information access on one of the NOAO machines that interested parties can "FTP" the latest news. For the moment you can e-mail the author for updates. This development is for the astronomical community at large as well as the USNO and NOAO. A production effort is planned as soon as the development is proved feasible and some idea of the yield and cost can be determined. I am collecting names of interested parties and institutions for use in establishing a production consortium. If you are interested, please contact me via e-mail and I will keep you posted. Aladdin Characteristics Number of Pixels 1024 (H) x 1024 (V) : 1,048,576 elements Pixel Size 27 um square Effective Fill Factor 100% Readout Type CMOS Control Logic using a PMOS SFD Number of Outputs 32 IR Detector Thinned InSb Wavelength Range 0.8 - 5 um Operating Temperature 35K Dark Current < 0.1 e-/sec Noise < 30 e- rms Full Well Capacity > 2 um 105 e- Readout Speed 20 frames/sec Quantum Efficiency > 80% 0.8 to 5 um Defective Pixels < 1.0% No Bad Rows or Columns A. M. Fowler I: afowler@noao.edu
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