C J Adkins

Bio: C J Adkins is an academic researcher. The author has contributed to research in topics: Variable-range hopping & Quantum tunnelling. The author has an hindex of 1, co-authored 1 publications receiving 112 citations.

Conduction in granular metals-variable-range hopping in a Coulomb gap?

Abstract: The author sets out the model for conduction in disordered systems by variable-range tunnelling in a Coulomb gap. Detailed analysis of experimental data for three different types of granular metal shows that the model cannot apply to these systems. He concludes that the problem of the mechanism of conduction in granular metals remains unsolved.

Electrical properties of TiO2 thin films

Abstract: The electrical properties of n-type titanium dioxide thin films deposited by magnetron-sputtering method have been investigated by temperature-dependent conductivity. We observed that the temperature dependence of the electrical conductivity of titanium dioxide films exhibits a crossover from T −1/4 to T −1/2 dependence in the temperature range between 80 and 110 K. Characteristic parameters describing conductivity, such as the characteristic temperature ( T 0 ), hopping distance ( R hop ), average hopping energy ( Δ hop ), Coulomb gap ( Δ C ), localization length ( ξ ) and density of states ( N ( E F )), were determined, and their values were discussed within the models describing conductivity in TiO 2 thin films.

Conductive Fibre Prepared From Ultra-High Molecular Weight Polyaniline for Smart Fabric and Interactive Textile Applications

Abstract: Panion™ fibre is prepared from a high molecular weight version of chlorine and defect free polyaniline (PANI). It is processed into textile fibre by continuous wet spinning techniques. The room temperature DC conductivity for unstretched and stretched (5x at 373 K) high molecular weight samples was 72 and 725 Ω −1 cm −1 , respectively. Resistivity measurements of Panion™, from 4 to 350 K, indicate that the fibre manufacturing process and the polymer synthetic route both serve to minimize structural disorder in the solid-state. The transport resides on the metallic side of the metal-insulator (M-I) phase boundary for unstretched and stretched fibre samples prepared from high M w PANI emeraldine base. The monofilament fibre can be formed into yarns for weaving fabric, braided into 2- and 3- dimensional structures, or used to form knitted fabrics, all with tunable electronic functionality.

Thermal evaporated Copper Iodide (CuI) thin films: A note on the disorder evaluated through the temperature dependent electrical properties

Abstract: Copper Iodide (CuI) thin films are p-type transparent conductors. In the present investigation, the physical properties of thermally evaporated (at 300 K) γ-phase copper iodide (CuI) thin films (of thickness 120 nm) prepared on the quartz substrates have been reported. The grain size (from SEM measurements) is ~ 80 nm. The (direct) optical band gap of CuI is 3.0 eV; the films show >70% transmission in the wavelength range 550–1000 nm and have low electrical resistance 72 mΩ cm. The Photo-luminescence spectra (with excitation wavelength 325 nm) shows a violet emission at ~ 409.4 nm (corresponds to the near band edge emission) and a shoulder peak centered at 417.4 nm (indicates the trap level near to the valence band edge induced by Iodine). The Hall mobility and carrier density of holes (from room temperature Hall measurements) in CuI thin films calculated are 1.46 cm2/V/s and 5.8×1019 cm−3 respectively. The disorder in the CuI thin films is evaluated by the temperature dependent (20–300 K) electrical resistivity measurements. The surface work-function of the CuI thin films measured by Kelvin probe technique; a non-destructive and sensitive surface analytical technique, is 4.71 eV (with reference to the gold probe).

The transient electrical conductivity of W-based electron-beam-induced deposits during growth, irradiation and exposure to air.

Abstract: W-based granular metals have been prepared by electron-beam-induced deposition from the tungsten hexacarbonyl W(CO)6 precursor. In situ electrical conductivity measurements have been performed to monitor the growth process and to investigate the behavior of the deposit under electron beam post-irradiation and by exposure to air. During the first part of the growth process, the electrical conductivity grows nonlinearly, independent of the electron beam parameters. This behavior is interpreted as the result of the increase of the W-particle's diameter. Once the growth process is terminated, the electrical conductivity decreases with the logarithm of time, ?~ln(t). Temperature-dependent conductivity measurements of the deposits reveal that the electrical transport takes place by means of electron tunneling either between W-metal grains or between grains and trap sites in the matrix. After venting the electron microscope the electrical conductivity of the deposits shows a degradation behavior, which depends on the composition. Electron post-irradiation increases the electrical conductivity of the deposits.