The time evolution of optically excited carriers in semiconductor quantum wells and quantum dots is analyzed for their interaction with LO phonons. Both the full two-time Green’s function formalism and the one-time approximation provided by the generalized Kadanoff-Baym ansatz are considered, in order to compare their description of relaxation processes. It is shown that the two-time quantum kinetics leads to thermalization in all the examined cases, which is not the case for the one-time approach in the intermediate-coupling regime, even though it provides convergence to a steady state. The thermalization criterion used is the Kubo-Martin-Schwinger condition.

• Received 20 October 2005

DOI:https://doi.org/10.1103/PhysRevB.73.115307