Nature of the Metal Insulator Transition in High-Mobility 2D_Si-MOSFETs.

Abstract

Our investigation focuses on the analysis of the conductive properties of high-mobility 2D-Si-MOSFETs as they approach the critical carrier density, nsc (approximately 0.72×1011 cm-2), which marks the metal insulator transition (MIT). In close proximity to the nsc, the conductivity exhibits a linear dependence on the temperature (T). By examining the extrapolated conductivity at the absolute zero temperature (T = 0), denoted as σ0, as a function of the electron density ns, we identify two distinct regimes with varying σ0(ns) patterns, indicating the existence of two different phases. The transition from one of these two regimes to another, coinciding with nsc, is abrupt and serves as the focus of our investigation. Our aim is to establish the possibility of a percolation type transition in the 2D-Si-MOSFETs' sample. In fact, we observed that the model of percolation is applicable only for densities very close to nsc*=n2 (where n2 is the linear extrapolation of σ0), indicating the percolation type transition essentially represents a phase transition at the zero temperature.