Tunneling lifetime broadening of the quantum well intersubband photoconductivity spectrum

We have measured, for the first time, the continuous infrared (λ∼10 μm) photoconductivity spectrum, for an intersubband absorption photoexcited tunneling quantum well detector. The line shape is broadened and asymmetrical with respect to the zero-bias Lorentzian absorption spectrum. We show that this is a result of the uncertainty principle lifetime broadening due to the rapid tunneling escape of the photoexcited electrons.