Browsing by Subject "Electronic transport"

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    Determination of the critical indium composition corresponding to the metal-insulator transition in InxGa1-xN (0.06 ≤ x ≤ 0.135) layers
    (Elsevier, 2009-10-13) Yildiz, A.; Lisesivdin, S. B.; Tasli, P.; Özbay, Ekmel; Kasap, M.
    The low-temperature conductivity of InxGa1-xN alloys (0.06 ≤ x ≤ 0.135) is analyzed as a function of indium composition (x). Although our InxGa1-xN alloys were on the metallic side of the metal-insulator transition, neither the Kubo-Greenwood nor Born approach were able to describe the transport properties of the InxGa1-xN alloys. In addition, all of the InxGa1-xN alloys took place below the Ioeffe-Regel regime with their low conductivities. The observed behavior is discussed in the framework of the scaling theory. With decreasing indium composition, a decrease in thermal activation energy is observed. For the metal-insulator transition, the critical indium composition is obtained as xc = 0.0543 for InxGa1-xN alloys.
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    Quantum transport regimes in quartic dispersion materials with Anderson disorder
    (AIP Publishing LLC, 2024-04-28) Polat, Mustafa; Özkan, Hazan; Sevinçli, Hâldun
    Mexican-hat-shaped quartic dispersion manifests itself in certain families of single-layer two-dimensional hexagonal crystals such as compounds of groups III-VI and groups IV-V as well as elemental crystals of group V. A quartic band forms the valence band edge in various of these structures, and some of the experimentally confirmed structures are GaS, GaSe, InSe, SnSb, and blue phosphorene. Here, we numerically investigate strictly one-dimensional and quasi-one dimensional (Q1D) systems with quartic dispersion and systematically study the effects of Anderson disorder on their transport properties with the help of a minimal tight-binding model and Landauer formalism. We compare the analytical expression for the scaling function with simulation data to distinguish the domains of diffusion and localization regimes. In one dimension, it is shown that conductance drops dramatically at the quartic band edge compared to the quadratic case. As for the Q1D nanoribbons, a set of singularities emerge close to the band edge, suppressing conductance and leading to short mean-free-paths and localization lengths. Interestingly, wider nanoribbons can have shorter mean-free-paths because of denser singularities. However, the localization lengths sometimes follow different trends. Our results display the peculiar effects of quartic dispersion on transport in disordered systems.