Electromagnetic Modeling and Design of Quantum Well Infrared Photodetectors

The quantum efficiency (QE) of a quantum well infrared photodetector (QWIP) is historically difficult to predict and optimize. This difficulty is due to the lack of a quantitative model to calculate QE for a given detector structure. In this paper, we found that by expressing QE in terms of a volumetric integral of the vertical electric field, the QE can be readily evaluated using a finite element electromagnetic solver. We applied this model to all known QWIP structures in the literature and found good agreement with experiment in all cases. Furthermore, the model agrees with other theoretical solutions, such as the classical solution and the modal transmission-line solution when they are available. Therefore, we have established the validity of this model, and it can now be used to design new detector structures with the potential to greatly improve the detector QE.