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3 September 2008 Low strain quantum dots in a double well infrared detector
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We report the fabrication of low strain quantum-dots-in-a-double-well (DDWELL) infrared photodetector where the net strain on the system has been reduced by limiting the total indium content in the system. The detector consists of InAs dots embedded in In0.15Ga0.85As and GaAs wells with a Al0.1Ga0.9As barrier, as opposed to In0.15Ga0.85As wells and a GaAs barrier in standard dots-in-a-well (DWELL) detector. The structure was a result of multilevel optimization involving the dot, well layers above and below the dot for achieving the desired wavelength response and higher absorption, and the thickness of the barriers for reduction in dark current. Detector structures grown using solid source molecular beam epitaxy (MBE) were processed and characterized. The reduction in total strain has enabled the growth of higher number of active region layers resulting in enhanced absorption of light. The detector shows dual color response with peaks in the mid-wave infrared (MWIR) and the long-wave infrared (LWIR) region. A peak detectivity of 6.7×1010 cm.√ Hz/W was observed at 8.7μm. The detector shows promise in raising the operating temperature of DWELL detectors, thereby enabling cheaper operation.
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R. V. Shenoi, J. Hou, Y. Sharma, J. Shao, T. E. Vandervelde, and S. Krishna "Low strain quantum dots in a double well infrared detector", Proc. SPIE 7082, Infrared Spaceborne Remote Sensing and Instrumentation XVI, 708207 (3 September 2008);

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