27 October 2010 Design and evaluation of a quantum-well-based resistive far-infrared bolometer
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To address the growing needs of the automotive industry for low cost solutions to far infrared imaging, a silicon - silicon germanium (Si/SiGe) quantum well resistive bolometer technology is presented. The Si/SiGe thermistor structure is epitaxially grown and combines a high temperature coefficient of resistance (TCR) with low flicker noise. A TCR of approximately 3%/K for a Ge fraction of 32% is demonstrated. Quantum mechanical calculations show that a minimum SiGe layer thickness of 8 nm is needed to avoid degradation caused by ground state shift due to carrier confinement in the SiGe potential wells. In contrast to most of today's bolometer designs, the optical quarter wave cavity needed to achieve high absorption of radiation is an integral part of the quantum well thermistor structure. Optimization of the full bolometer design is made where the interaction between optical absorption, heat capacity and electrical properties is considered and a design approach targeting the lowest noise equivalent temperature difference is presented. As part of the optimization, it was found that for the best overall solution, optical absorption can be sacrificed in favor for a smaller heat capacity.
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Per Ericsson, Per Ericsson, Linda Höglund, Linda Höglund, Björn Samel, Björn Samel, Susan Savage, Susan Savage, Stanley Wissmar, Stanley Wissmar, Olof Öberg, Olof Öberg, Jan-Erik Källhammer, Jan-Erik Källhammer, Dick Eriksson, Dick Eriksson, } "Design and evaluation of a quantum-well-based resistive far-infrared bolometer", Proc. SPIE 7834, Electro-Optical and Infrared Systems: Technology and Applications VII, 78340Q (27 October 2010); doi: 10.1117/12.865036; https://doi.org/10.1117/12.865036

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