Role of doped layers in the dephasing of two-dimensional electrons in quantum-well structures

The temperature and gate voltage dependences of the phase breaking time are studied experimentally in GaAs/InGaAs heterostructures with a single quantum well. It is shown that appearance of states at the Fermi energy in the doped layers leads to a significant decrease of the phase breaking time of the carriers in the quantum well and to saturation of the phase breaking time at low temperature.