INFLUENCE OF COLLECTIVE EFFECTS ON THE LINEWIDTH OF INTERSUBBAND RESONANCE

We have measured the intersubband resonances of an InAs/AlSb quantum w ell with two occupied subbands from cryogenic temperatures to well abo ve room temperature. The higher energy mode is very robust with increa sing temperature; the lower energy mode, however, broadens above 200 K . We explain the results in terms of Landau damping and argue generall y that the collective nature of the intersubband resonance is crucial for an understanding of the scattering mechanisms that determine the i ntersubband resonance linewidth.