Abstract
The use of intersubband transitions in quantum cascade structures for thermophotovoltaic energy conversion is investigated numerically. The intrinsic cascading scheme, spectral agility, and design flexibility of these structures make them ideally suited to the development of high efficiency multiple-junction thermophotovoltaic detectors. A specific implementation of this device concept is designed, based on bound-to-continuum intersubband transitions in large-conduction-band-offset In(0.7)Ga(0.3)As/AlAs(0.8)Sb(0.2) quantum wells. The device electrical characteristics in the presence of thermal radiation from a blackbody source at 1300 K are calculated, from which a maximum extracted power density of 1.4 W/cm(2) is determined. This value compares favorably with the present state-of-the-art in interband thermophotovoltaic energy conversion, indicating that quantum cascade photodetectors may provide a promising approach to improve energy extraction from thermal sources.
Highlights
Intersubband (ISB) transitions in semiconductor quantum wells (QWs) offer several attractive features for optoelectronic device development [1], in the mid- and far-infrared spectral regions where they can be used to overcome some of the intrinsic limitations of narrow-bandgap materials
ISB transitions already form the basis of well established devices such as quantum cascade lasers (QCLs) and quantum-well infrared photodetectors (QWIPs)
In this work we study the design and limiting performance of multiple-junction TPV devices based on the quantum cascade photodetector (QCP) concept
Summary
Intersubband (ISB) transitions in semiconductor quantum wells (QWs) offer several attractive features for optoelectronic device development [1], in the mid- and far-infrared spectral regions where they can be used to overcome some of the intrinsic limitations of narrow-bandgap materials. Higher limiting efficiencies can be obtained with the use of cascaded multiple junctions of different bandgap energy, each providing efficient conversion of near-bandgap radiation over a different photon-energy range [9] This approach is already well established, in the context of solar cells, its implementation is complicated by various material and design issues. This device involves four different stage architectures providing photovoltaic detection over four adjacent spectral regions. From these results, the device ability to produce electrical power is evaluated and found to compare favorably with the present state-of-the-art in TPV energy conversion.
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