Critical Behavior of a Strongly Disordered 2 D Electron System: The Cases of Long-Range and Screened Coulomb Interactions

A study of the temperature (T) and density (n(s)) dependence of conductivity sigma(n(s), T) of a highly disordered, two- dimensional (2D) electron system in Si demonstrates scaling behavior consistent with the existence of a metal-insulator transition (MIT). The same critical exponents are found when the Coulomb interaction is screened by the metallic gate and when it is unscreened or long range. The results strongly suggest the existence of a disorder-dominated 2D MIT, which is not directly affected by the range of the Coulomb interactions.