Electrical Properties Of Zinc Oxide Research Articles

Tailoring Electrical Conductivity and Mechanism of Carrier Transport in Zinc Oxide with Embedded Ag Layer

ABSTRACTThe effects of an embedded silver layer on the electrical properties of zinc oxide (ZnO) / silver (Ag)/ zinc oxide (ZnO) layered composite structures on polymer substrates have been investigated. We have engineered transparent conducting oxide structures with greatly improved conductivity. Electrical properties are correlated with Ag thickness. Film thicknesses were determined using Rutherford backscattering spectrometry. Hall effect, 4-point probe, and UV-Vis spectrophotometer analyses were used to characterize electrical and optical properties. The results show that carrier concentration, mobility, and conductivity increase with Ag thickness. Increasing Ag thickness from 8 to 14 nm enhances sheet resistance and resistivity by six orders of magnitude. We describe of the influence of Ag thickness on electrical properties of the ZnO/Ag/ZnO composite and propose a conduction mechanism for this system.

Preparation, structural and electrical properties of zinc oxide grown on silicon nanoporous pillar array

Polycrystalline thick film of zinc oxide (ZnO) is grown on a unique silicon substrate with a hierarchical structure, silicon nanoporous pillar array (Si-NPA), by using a vapour phase transport method. It is found that as-grown ZnO film is composed of closely packed ZnO crystallites with an average size of ~10μm. The film resistivity of ZnO/Si-NPA is measured to be ~8.9Ω·cm by the standard four probe method. The lengthwise I-V curve of ZnO/Si-NPA heterostructure is measured. Theoretical analysis shows that the carrier transport across ZnO/Si-NPA heterojunction is dominated by two mechanisms, i.e. a thermionic process at high voltages and a quantum tunnelling process at low voltages.

Nanoscale surface electrical properties of zinc oxide films investigated by conducting atomic force microscopy

In this study, conducting atomic force microscopy was employed to investigate the nanoscale surface electrical properties of zinc oxide (ZnO) films prepared by pulsed laser deposition (PLD) at different substrate temperatures for use as anode materials in polymer light-emitting diodes. The results show that the surface conductivity distribution of ZnO is related to its surface structure. At substrate temperatures of 150-200 degrees C, the conducting regions may cover over 90% of the ZnO thin-film surface, thus providing the best local conductivity. Moreover, heating at substrate temperatures of above 250 degrees C can effectively make the conductivity on the ZnO surface uniform. In particular, at substrate temperatures of around 300 degrees C, the conducting regions where currents are between 1 and 2 muA may cover as much as 83% of the surface, and furthermore, the transmission ratio in the visible range is higher than 80%. This is a rather ideal production temperature for the PLD for ZnO films.

Lowered stimulated emission threshold of zinc oxide by hydrogen doping with pulsed argon–hydrogen plasma

The effects of hydrogen doping on the optical and electrical properties of zinc oxide (ZnO) films were investigated. We prepared about 50-nm thick ZnO films on a sapphire substrate by using a pulsed laser deposition method and used a pulse-modulated inductively coupled plasma technique (PM-ICP) to intentionally insert hydrogen into the films. An increase in the electron concentration by hydrogen doping indicated that hydrogen is actually a cause of shallow donors. Moreover, the excitation intensity threshold for optically pumped stimulated emissions was significantly reduced after hydrogen doping.

Bias 전압에 따른 ZnO:Al 투명전도막의 전기적 특성

Recently zinc oxide(ZnO) has emerged as one of the most promising transparent conducting films with a strong demand of low cost and high performance optoelectronic devices, ZnO film has many advantages such as high chemical and mechanical stabilities, and abundance in nature. In this paper, in order to obtain the excellent transparent conducting film with low resistivity and high optical transmittance for Plasma Display Pannel(PDP), aluminium doped zinc oxide films were deposited on Corning glass substrate by dc magnetron sputtering method. The effects of the discharge power and doping amounts of <TEX>$Al_2$</TEX><TEX>$O_3$</TEX> on the electrical and optical properties were investigated experimentally. Particularly in order to lower the electrical resistivity, positive and negative bias voltages were applied on the substrate, and the effect of bias voltage on the electrical properties of ZnO:Al thin film were also studied and discussed. Films with lowest resistivity of <TEX>$4.3 \times 10 ^{-4} \Omega-cm$</TEX> and good transmittance of 91.46 % have been achieved for the films deposited at 1 mtorr, <TEX>$400^{\circ}C$</TEX>, 40 W, Al content of 2 wt% with a substrate bias of +30 V for about 800 nm in film thickness.

Electrical properties of zinc oxide sputtered thin films

ZnO thin films were deposited on silicon substrate by rf magnetron sputtering from metallic zinc target. The electrical properties of ZnO are currently being studied. In this work, measurements of the ac conductivity properties of ZnO sandwich structures with silver and platinum electrodes are reported. The frequency dependence of both the ac conductivity and dielectric constant of thin films of ZnO have been investigated in the frequency range 5kHz–13 MHz. It is shown that the total ac conductivity σ(ω), obeys the equation σ(ω)=AωS where s is an index which increases with frequency and decreases with temperature. It appears that for ZnO films, the conduction mechanism is thermally activated and both the overlap large polaron tunnelling and the correlated barrier-hopping of charge carrier over localized states fit the experimental data. The dielectric constant, εr, lies in the range 8–9 at room temperature and is independent of the frequency in the dielectric thin films.