InSb arrays for IRAC (InfraRed Array Camera) on SIRTF (Space Infrared Telesope Facility)

SIRTF requires detector arrays with extremely high sensitivity, limited only by the background irradiance. Especially critical is the near infrared spectral region around 3 μm, where the detector current due to the zodiacal background is a minimum. IRAC has two near infrared detector channels centered at 3.6 and 4.5 μm. We have developed InSb arrays for these channels that operate with dark currents of <0.2 e/s and multiply-sampled noise of ~7 e at 200s exposure. With these specifications the zodiacal background limited requirement has been easily met. In addition, the detective quantum efficiency (DQE) of the InSb devices exceeds 90% over the IRAC wavelength range, they are radiation hard, and they exhibit excellent photometric accuracy and stability. Residual images have been minimized. The Raytheon 256 x 256 InSb arrays incorporate a specially developed (for SIRTF) multiplexer and high-grade InSb material.