<title>32-pixel FIRGA demonstrator: testing of a gallium arsenide photoconductor array for far-infrared astronomy</title>

Abstract

A gallium arsenide photoconductive detector, which is sensitive in the far-infrared wavelength range from approximately 60 micrometers to 300 micrometers , offers the advantage of extending considerably the long wavelength cut-off of presently available photodetectors. FIRGA is an ESA sponsored GaAs detector development program which is approaching completion. The FIRGA study is intended to prepare the technology for large 2D GaAs detector arrays for far-infrared astronomy. The primary goal of the development is the preparation of a monolithic 32 element demonstrator array module with associated cryogenic read-out electronics. Continuous progress in material research has led to the production of pure and doped n-type GaAs layers using liquid phase epitaxy. We prepared sample detectors from those materials and investigated their electrical and infrared characteristics. Finally, a multi-layer structured detector device was manufactured. The 4 X 8 element array configuration is defined by sawing a split pattern into the layers with pixel size 1 mm X 1 mm. The device is back illuminated. The 32 pixels are connected to two cryogenic read-out electronics chips mounted close-by. Results of the initial detector performance tests are reported. We determined dark current, responsivity and response transients. Ongoing development activities will concentrate on material research, i.e. the production of n-GaAs layers of ultra-high purity and those with improved FIR characteristics using new centrifugal techniques for material growth.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.