Linear temperature dependence of conductivity in Si two-dimensional electrons near the apparent metal-to-insulator transition

Abstract

In a high mobility two-dimensional electron system in Si, near the critical density, $n_c=0.32\times 10^{11}$cm${}^{-2}$, of the apparent metal-to-insulator transition, the conductivity displays a linear temperature ($T$) dependence around the Fermi temperature. When ${\sigma }_0$, the extrapolated T=0 conductivity from the linear T-dependence, is plotted as a function of density, two regimes with different ${\sigma }_0(n)$ relations are seen, suggestive of two different phases. Interestingly, a sharp transition between these two regimes coincides with $n_c$, and ${\sigma }_0$ of the transition is $\sim$ $e^2/h$, the quantum conductance, per square. Toward T=0, the data deviate from linear $\sigma (T)$ relation and we discuss the possible percolation type of transition in our Si sample.

4 Revtex pages, 3 figures

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• Transport in strongly correlated two dimensional electron fluids
• The Observation of Percolation-Induced 2D Metal-Insulator Transition in a Si MOSFET
• Flow diagram of the metal-insulator transition in two dimensions
• Incipient Wigner Localization in Circular Quantum Dots
• Screening and transport in 2D semiconductor systems at low temperatures
• Two-dimensional metal-insulator-transition as a potential fluctuation driven semiclassical transport phenomenon
• Self-doping instability of the Wigner-Mott insulator
• Degenerate versus semi-degenerate transport in a correlated 2D hole system
• Termination of two-dimensional metallic conduction near metal-insulator transition in a Si/SiGe quantum well
• Indications for sharp continuous phase transitions at finite temperatures connected with the apparent metal-insulator transition in two-dimensional disordered systems
• Impact of Short-Range Scattering on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells
• Indications for a line of continuous phase transitions at finite temperatures connected with the apparent metal-insulator transition in 2d disordered systems
• Surprising coincidence of the apparent 2D metal-to-insulator transition data with Fermi-gas based model results