Metal-insulator transition in tin doped indium oxide (ITO) thin films: Quantum correction to the electrical conductivity

Abstract

Tin doped indium oxide (ITO) thin films are being used extensively as transparent conductors in several applications. In the present communication, we report the electrical transport in DC magnetron sputtered ITO thin films in low temperatures (25-300 K). The low temperature Hall effect and resistivity measurements reveal that the ITO thin films are moderately dis-ordered (k f l~1) and degenerate semiconductor. The transport of charge carriers in these disordered ITO thin films takes place via the de-localized states. The disorder effects lead to the well-known metal-insulator transition; this transition is observed at 110 K in ITO thin films. The metalinsulator behaviour is explained by the quantum correction to the conductivity (QCC); this approach is based on the quantum-mechanical interference effects in the disordered systems. The insulating behaviour is attributed to the combined effect of the weak localization and the electron-electron interactions.

Epitaxially Oriented Sn:In2O3 Nanowires Grown by the Vapor–Liquid–Solid Mechanism on m-, r-, a-Al2O3 as Scaffolds for Nanostructured Solar Cells

“…Consequently, a reduction in temperature will not result in a significant change in carrier density, similar to the case of metals. This has been observed in temperature-dependent measurements of the carrier density and conductivity of both Sn:In 2 O 3 NWs and ITO layers. − As such, the native defects in the Sn:In 2 O 3 NWs are not expected to contribute strongly to the overall conductivity. To gain a better understanding of the charge distribution in the Sn:In 2 O 3 NWs, we have calculated the conduction band (CB) potential profile along the radial direction but also the energetic position of the one-dimensional sub-bands and one-dimensional electron gas (1DEG) charge distribution via the self-consistent solution of the Poisson–Schrödinger (SCPS) equations in the effective mass approximation.…”

Nonvolatile Control of the Electronic Properties of In2–xCrxO3 Semiconductor Films by Ferroelectric Polarization Charge

“…The k f l values are larger than 1, implying the weak localization (WL) effect of disordered systems . The MST in the undoped In 2 O 3 film has also been observed in other wide band gap (e.g., ITO and ZnO) and analyzed in the frame of the quantum correction to conductivity (QCC) in a disordered system. − In this frame, the QCC for a three-dimensional system at a low temperature is given by where σ 0 = 1/ρ 0 (ρ 0 is the residual resistivity), AT p /2 expresses the contribution from the WL effect due to the self-interference of quantum wave functions backscattered on impurities, and p depends on the nature of the interactions, where p = 2 for the electron–electron interaction (EEI) and p = 3 for the electron–phonon interaction at low temperatures. BT 1/2 represents the contribution from the EEI effect.…”

Interaction of an Ultrathin Zinc Surface Passivation Layer with a Room Temperature-Deposited Al-Doped ZnO Film Leading to Highly Improved Electrical Transport Properties

“…Let us now discuss the conduction mechanism of 2AZO5.3 film having K F l = 1.56, which suggests very less disorderinduced localization of the system as compared to the other two. For metal, the well-known Boltzmann transport equation can be expressed as 65 where ρ 0 is the resistivity at T → 0, and K is a constant. The observed MST of 2AZO5.3 can be explained in the framework of quantum corrections to conductivity (QCC) to the classical Boltzmann equation for metal.…”