Subband mobilities and Dingle temperatures within a two-subband model in the presence of localized states

We calculate the transport time and the single-particle relaxation times in a two subband system of a two-dimensional electron gas. We take into account screening and density of states effects under the assumption that disorder leads to localized states in both subbands. We find that the single-particle relaxation time of the second subband is always larger than for the first subband.The transport time of the second subband can be smaller or larger than the transport time of the first subband.