2K×2K NIR HgCdTe Detector Arrays for VISTA and Other Applications

摘要

The demand for large - format NIR arrays has grown for both ground - based and space - based applications. These arrays are required for maintaining high resolution over very large fields of view for survey work. We describe results of the development of a 2048×2048 HgCdTe/CdZnTe array with 20 micron pixels that responds with high Quantum Efficiency (QE) over the wavelength range of 0.85 to 2.5 microns. With a single-layer antireflection coating, the responsive QE is greater than 70% from 0.9 micron to 2.4 microns. Dark current is typically less than le~-/sec at 80 K. The modular package for this array, dubbed the VIRGO array, allows three-side butting to form larger mosaic arrays of 4K×2nK format. The VIRGO ROIC utilizes a PMOS Source Follower per Detector (SFD) input circuit with a well capacity of about 3×10~5 electrons and with a read noise of less than 20 e~- rms with off-chip Correlated Double Sampling (CDS). Other features of the VIRGO array include 4 or 16 outputs (programmable), and a frame rate of up to 1.5 Hz in 16-output mode. Power dissipation is about 7 mW at a 1 Hz frame rate. Reset modes include both global reset and reset by row (ripple mode). Reference pixels are built-in to the output data stream. The first major application of the VIRGO array will be for VISTA, the UK's Visible and Infrared Survey Telescope for Astronomy. Raytheon Vision Systems has completed delivery of 16 Science Grade arrays and four Engineering arrays to VISTA. The VISTA FPA will operate at near 80 K. The cutoff wavelength of the HgCdTe detector can be adjusted for other applications. Space applications include SNAP, the Supernova/Acceleration Probe, which requires a shorter detector cutoff wavelength of 1.7 microns. For applications which require both visible and NIR response, the detector CdZnTe substrate can be removed after hybridization, allowing the thinned detector to respond to visible wavelengths as short as 0.4 microns.