Polarized front-illumination response in intraband quantum dot infrared photodetectors at 77 K - art. no. 045323

Multicolor quantum dot infrared photodetectors with normal incidence backgr ound limited performance (BLIP) at 77 K were implemented. The devices are c omposed of self-assembled InAs dots grown on InAlAs barrier layers, lattice matched to InP substrate. These dots are formed in a shape of flattened pa rallelepipeds. The photoconductive spectra were observed at all polarizatio ns. Normal incidence photocurrent spectra reveal several polarized peaks in the range of 100-400 meV due to intersubband transitions. The detector res ponsivity at normal incidence is similar to that obtained for polarization normal to the layers, and is comparable to that achieved in quantum well in frared photodetectors (QWIP's). The transition energies, the polarization s election rules, and relative intensities of the peaks were tentatively inte rpreted in terms of a three-dimensional separation of variables.