Theoretical study of quantum well infrared photodetectors with asymmetric well and barrier structures for broadband photodetection

The n-type InGaAs/AlxGa1−xAs quantum well infrared photodetector QWIP with asymmetric graded barriers for broadband detection has been investigated theoretically based on the eight-band k·p model. It is found that the intersubband transitions from the ground state to all bound and continuum excited states contribute to the overall absorption and the bound-to-continuum B-to-C transitions dominate. The superposition of the bound-to-bound and B-to-C transitions results in a broad detection bandwidth, and both the detected wavelength and bandwidth can be tuned by the applied voltage. The analysis method is also applicable to the GaAs/ InxGa1−xAs/ InyGa1−yAs QWIP with step quantum wells. The calculated results are consistent with the reported experimental observations.Published versio