Tuning of the single-particle relaxation time of a high mobility electron gas in a Ga0.25In0.75As/InP quantum well

Two different scattering mechanisms determine the momentum relaxation time, tau, and the single particle relaxation time, tau(s), of the electrons in a modulation doped Ga0.25In0.75As/InP quantum well. We show that tau is mainly limited by ahoy disorder scattering, while tau(s) is determined by the remote ionized impurity scattering rate. This means that the Ga0.25In0.75As/InP material system offers the unique possibility of tuning tau(s) by varying the distance between the modulation doped layer and the two-dimensional electron gas, while tau is kept constant. The variation of tau(s) can thus be monitored, for example, by observing the appearance of spin-split Landau levels, at different magnetic fields, as a function of spacer layer width. (C) 1997 American Institute of Physics.