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

The transport time and the single-particle relaxation times in a two subband system of a two-dimensional electron gas have been calculated. Screening and density of states effects have been taken into account under the assumption that disorder leads to localized states in both subbands. It has been found that the single-particle relaxation time of the second subband is always larger than that for the first subband. The transport time of the second subband can be smaller or larger than the transport time of the first subband. The text was submitted by the authors in English.