Origin Of Electrical Conductivity Research Articles

Multifunctional P-Doped TiO2 Films: A New Approach to Self-Cleaning, Transparent Conducting Oxide Materials

Multifunctional P-doped TiO2 thin films were synthesized by atmospheric pressure chemical vapor deposition (APCVD). This is the first example of P-doped TiO2 films with both P5+ and P3– states, with the relative proportion being determined by synthesis conditions. This technique to control the oxidation state of the impurities presents a new approach to achieve films with both self-cleaning and TCO properties. The origin of electrical conductivity in these materials was correlated to the incorporation of P5+ species, as suggested by Hall Effect probe measurements. The photocatalytic performance of the films was investigated using the model organic pollutant, stearic acid, with films containing predominately P3– states found to be vastly inferior photocatalysts compared to undoped TiO2 films. Transient absorption spectroscopy studies also showed that charge carrier concentrations increased by several orders of magnitude in films containing P5+ species only, whereas photogenerated carrier lifetimes—and thus...

Low substrate temperature fabrication of high-performance metal oxide thin-film by magnetron sputtering with target self-heating

Al-doped ZnO (AZO) films with high transmittance and low resistivity were achieved on low temperature substrates by radio frequency magnetron sputtering using a high temperature target. By investigating the effect of target temperature (TG) on electrical and optical properties, the origin of electrical conduction is verified as the effect of the high TG, which enhances crystal quality that provides higher mobility of electrons as well as more effective activation for the Al dopants. The optical bandgap increases from 3.30 eV for insulating ZnO to 3.77 eV for conducting AZO grown at high TG, and is associated with conduction-band filling up to 1.13 eV due to the Burstein–Moss effect.

On the origin of electrical conductivity in the bio-electronic material melanin

The skin pigment melanin is one of a few bio-macromolecules that display electrical and photo-conductivity in the solid-state. A model for melanin charge transport based on amorphous semiconductivity has been widely accepted for 40 years. In this letter, we show that a central pillar in support of this hypothesis, namely experimental agreement with a hydrated dielectric model, is an artefact related to measurement geometry and non-equilibrium behaviour. Our results cast significant doubt on the validity of the amorphous semiconductor model and are a reminder of the difficulties of electrical measurements on low conductivity, disordered organic materials.

The effect of annealing processes on electronic properties of sol-gel derived Al-doped ZnO films

Al-doped ZnO films with high transmittance and low resistivity were prepared by sol-gel method with a three-step annealing. By investigating the relative effect of the Al∕Zn ratio to the annealing on electrical and optical properties, the origin of electrical conduction is verified as the combining effect of the high temperature annealing which enhances crystal quality that provides higher mobility of electrons and the reduction annealing which releases the localized electrons caused by oxygen absorption. Varying the Al∕Zn ratio causes a small Burstein–Moss shift and a slight change in carrier concentration. In contrast, the annealing procedure produces significant changes in the carrier concentration and mobility.

Electrical conduction and superconductivity

The article discusses the origin of electrical conduction and resistance in metals. It also discusses superconductivity in metals and the underlying mechanism. The salient features of high temperature superconductivity are mentioned and difficulties in understanding the mechanism of high temperature superconductivity are briefly discussed.

Electrical properties of sodium phosphate glasses containing Al 2O 3 and/or Fe 2O 3. Part II

The electrical properties for three series of glasses: xNa 2O–(40− x)Al 2O 3–60P 2O 5, (20⩽ x⩽35), (NAP); 20Na 2O– xAl 2O 3–(20− x)Fe 2O 3–60P 2O 5, (5⩽ x⩽15), (NAFP), and xNa 2O–(40− x)Fe 2O 3–60P 2O 5, (20⩽ x⩽35), (NFP) glasses were measured by impedance spectroscopy in the frequency range from 1 Hz to 1 MHz and over the temperature range from 303 to 473 K. It was shown (in Part I) that the addition of Fe 2O 3 has significant effects on the structure of these glasses and Fe ions play a different structural role in phosphate network than that of Al ions. Such effects reflect changes in the origin of electrical conduction. With increasing Fe 2O 3 content in NAFP and NFP glasses the dc conductivity depends upon distance between iron ions and the activation energy of 53.1 kJ mol −1 indicates electronic conduction. On the other hand, the decrease in dc conductivity and activation energy for glasses in NAP series is attributed to the decrease in Na 2O content from 35 to 20 mol%. The activation energy varies from 80.1 to 72.4 kJ mol −1 for NAP glasses suggesting ionic conduction. The impedance analysis for these glasses shows that the changes in the electrical conduction mechanisms coincide with the changes in the structure.

Electrical properties of an epoxy resin during and after curing

AbstractBy means of an epoxynovolac resin with BF3 complex the suitability of measurements of electrical properties for the investigation of curing process and for the evaluation of cured resins is illustrated. The origin of electrical conductivity and polarization is elucidated.