Frozen electron solid in the presence of small concentrations of defects

We investigate the freezing of a low-density electron liquid for a two-dimensional electron layer in the presence of low levels of defects typical of a high-quality semiconductor interface. We use a memory function approach with mode-coupling approximation and include the effect of strong electron-electron correlations, which we find are crucial for the transition. For a range of low impurity concentrations we find a stable frozen solid with a liquidlike short-range order. At higher impurity concentrations the electrons localize separately and there is no short-range order. Our electron-density vs peak-mobility phase diagram at zero temperature is in agreement with recent metal-insulator transition experiments in silicon heterostructures.