Signatures of localization in the effective metallic regime of high mobility Si MOSFETs

Abstract

Combining experimental data, numerical transport calculations, and theoretical analysis, we study the temperature-dependent resistivity of high-mobility 2D Si MOSFETs to search for signatures of weak localization induced quantum corrections in the effective metallic regime above the critical density of the so-called two-dimensional metal-insulator transition (2D MIT). The goal is to look for the effect of logarithmic insulating localization correction to the metallic temperature dependence in the 2D conductivity so as to distinguish between the 2D MIT being a true quantum phase transition versus being a finite-temperature crossover. We use the Boltzmann theory of resistivity including the temperature dependent screening effect on charged impurities in the system to fit the data. We analyze weak perpendicluar field magnetoresistance data taken in the vicinity of the transition and show that they are consistent with weak localization behavior in the strongly disordered regime $k_F\ell \gtrsim 1$. Therefore we supplement the Botzmann transport theory with a logarithmic in temperature quantum weak localization correction and analyze the competition of the insulating temperature dependence of this correction with the metallic temperature dependence of the Boltzmann conductivity. Using this minimal theoretical model we find that the logarithmic insulating correction is masked by the metallic temperature dependence of the Botzmann resistivity and therefore the insulating $\log T$ behavior may be apparent only at very low temperatures which are often beyond the range of temperatures accessible experimentally. Analyzing the low-$T$ experimental Si MOSFET transport data we identify signatures of the putative insulating behavior at low temperature and density in the effective metallic phase.

10 pages,5 figures, published version

References in corpus (5)

• Metal-insulator transition in two-dimensional electron systems
• The Observation of Percolation-Induced 2D Metal-Insulator Transition in a Si MOSFET
• Coherent back-scattering near the two-dimensional metal-insulator transition
• Intervalley scattering and weak localization in Si-based two-dimensional structures
• Interplay between phonon and impurity scattering in 2D hole transport

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• Density-tuned effective metal-insulator transitions in 2D semiconductor layers: Anderson localization or Wigner crystallization
• Metallic State of Low Mobility Silicon at High Carrier density induced by an Ionic Liquid
• Understanding disorder in Silicon quantum computing platforms: Scattering mechanisms in Si/SiGe quantum wells
• Integer Quantum Hall Effect: Disorder, temperature, floating, and plateau width
• Anderson localization crossover in 2D Si systems: The past and the present
• Bound state-continuum resonance transition in a shallow quantum well