Influence of DX center structure on Si modulation delta-doping in AlGaAs/GaAs quantum wells.

It has been observed that the achievable 2D electron concentration, in delta-doped quantum wells, depends on the Aluminium concentration in the doping region. So far, this behavior was attributed to a changing incoorporation of the Si dopant. We show instead that the energy levels of the DX center along with the Coulombic interaction account for this behavior. We present calculations of the DX center density of states due to potential fluctuations and show that the estimated 2D concentrations agree quit well with our experimental results.