Gating versus doping: Quality parameters of two-dimensional electron systems in undoped and doped GaAs/AlGaAs heterostructures

We present an experimental study of the scattering mechanisms in a two-dimensional electron system which is either fully induced by the field effect or resulting from remote doping. The quality criteria-the electron mobility, the quantum scattering time, and the number and development of certain fractional quantum Hall states-are analyzed and compared. By eliminating the scattering off remote ionized impurities (RI) in undoped systems, we can identify the density regimes most susceptible to RI scattering and their impact on the formation of fractional quantum Hall states.