Eight-element-stressed Ge:Ga linear array: development and performance

AbstractWe have developed an eight-element stressed Ge:Ga linear array. It has a compact and stable structure. Thepixel size is 0.9 x 0.9 x 0.9 mm3, the pitch of the array is 1.0 mm, and the total sensitive area is 8.0 mmx 1.0 mm. The longer wavelength cut-off is 200 microns, and the peak responsivity is 100 A/W in a high-background condition including cavity efficiencies. It has been demonstrated that this array has a useful performance in the high-background condition,such as for air-borne and balloon-borne instruments. The structure of the stress assembly is provably extendable up to sixteen and more.1. INTRODUCTION In the far-infrared wavelength region, Ge:Ga photoconductors are the most sensitive detectors and have been producing a lot of fruitful astronomical results so far. However, the Ge:Ga has a longer wavelength cut-off around at 120 microns while, applying some stress, we can shift the longer wavelength cut-off up to 200 microns. In the far-infrared region, we have another good detector, bolometer. However, the bolometers need to be cooled down to sub Kelvin in orderto get a good sensitivity comparable to the stressed Ge:Ga. Therefore, we usually use the stressed Ge:Ga between 120 and200 microns.