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4 March 2010 A floating gate double quantum well far-infrared photoconductor
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The design and characterization of a floating gate GaAs/AlGaAs double quantum well long-infrared photoconductor is reported, with record operating temperature and modulation bandwidth for a device of this type. The principle of device operation relies on the photoionization of one quantum well, which functions as a floating gate, to modulate the conductance of the underlying quantum well, which functions as a transistor channel. Photoionization under normal incidence illumination is facilitated by a metal grating. Responsivity of 80-160 A/W for 12-20 μm long-infrared radiation has been observed at a 10 K device temperature, and photoresponse is clearly discernable up to 30 K. The modulation bandwidth was measured to exceed 1 kHz. An NEP = 2×10-11 W/ square root Hz, and D* = 4×108 cm square root Hz/W were measured, as limited by quantum well conductance fluctuations. Device performance is in fair competition with conventional QWIPs and we also propose a method to increase input saturation power in a photodetector of this structure.
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Elizabeth Ledwosinska and Thomas Szkopek "A floating gate double quantum well far-infrared photoconductor", Proc. SPIE 7601, Terahertz Technology and Applications III, 76010J (4 March 2010);

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