New infrared-sensor chip.
In the new device, indium antimonide replaces silicon, shifting the chip's spectral sensitivity into the 3 to 5 micron IR range. Though 1,024 pairs of metal-insulated semiconductor capacitors share a chip just 0.116 inch by 0.318 inch, placing a lens in front of it enables the device to image a large area in detail, according to Ching-Yeu Wei, its primary developer.
Two capacitors form each energy-gathering pixel. One picks up the faint IR signal, storing it as an electric charge. For the chip to report that signal, the charge must be transferred to a readout capacitor. To double or more the charge-transfer efficiency of this chip--and with that, its sensitivity--each capacitor duo has been designed as a concentric ring instead of a side-by-side pair. Also aiding efficiency is its planar topography; the usual deep etched hills and valleys can sometimes trap a charge and prevent it from transferring, Wei notes.
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|Date:||Feb 9, 1985|
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