Phonon limited intersubband lifetimes and linewidths in a two-dimensional electron gas

Abstract

Using an excited‐state induced absorption spectroscopy technique, we have measured the lifetime of a state separated from the ground state by less than the optical phonon energy in a modulation‐doped structure. A lifetime of τ=(300±100) ps is found in agreement with the prediction for the emission of an acoustic phonon. Moreover, we report the first direct evidence of a lifetime‐broadened intersubband absorption line with a full width at half‐maximum of 2.66 meV for a transition energy of E₁₃=136 meV.