Fano profile in intersubband transitions in InAs quantum dots

We have investigated the infrared photocurrent spectra due to bound-to-continuum intersubband transitions in self-assembled InAs/GaAs quantum dots. It is found that the observed photocurrent spectra exhibit a broad peak followed by a peculiar quenching of their intensity at photon energy around 370 meV. We theoretically demonstrate that such a strong modulation of the intersubband transition spectra is due to Fano resonance which results from the quantum mechanical interference within the continuum. The calculated intersubband transition spectrum is in excellent agreement with experiments.