Interaction-Induced Transition at Low Densities in Silicon Inversion Layer

Intravalley exchange and correlation are found to induce a first-order transition at low densities in the inversion layer, lowering the valley degeneracy. For the $n$ channel on Si(100) surface, the reduction from two valleys to one occurs roughly below 3×${10}^{11}$ ${\mathrm{cm}}^{-2\mathrm{}}$. The one-valley phase with domain structure yields activated conductivity and other observed low-density behavior.