Polarized front-illumination response in quantum dot infrared photodetectors

In this work we demonstrated multicolor quantum dot infrared photodetectors with normal incidence background limited performance (BLIP) at 70 K. The devices, which were studied in this work, were composed of self-assembled InAs dots grown by MBE on InAlAs barrier lattice matched to InP substrate. Normal incidence photocurrent spectra reveal several polarized and unpolarized peaks in the range 100-350 meV due to the intersubband transitions. The detector responsivity at normal incidence is similar to that obtained for polarization normal to the layers, and is comparable to that achieved in quantum well infrared photodetectors.