Detection techniques for tenuous planetary atmospheres Semiannual report, 1 Jul. - 31 Dec. 1968

Absorption and desorption of oxygen by zinc oxide film irradiated by ultraviolet ligh

Transfer Length Measurements For Different Metallization Options And Processing Of Gallium Tin Zinc Oxide (Gszo) Tfts

Transfer length measurements for various metal contacts on gallium tin zinc oxide film have been performed in this work to determine the specific contact resistivity. The investigated contacts are Al (100nm), Ti (20nm)/Al (30 nm)/Au (100nm) and Al (30nm)/ Au (50nm) and Al (30nm)/ Pt (50nm)

On the relevance of large scale pulsed-laser deposition: Evidence of structural heterogeneities in ZnO thin films

Pulsed-laser deposition is known as a well-suited method for growing thin films of oxide compounds presenting a wide range of functional properties. A limitation of this method for industrial process is the very anisotropic expansion dynamics of the plasma plume, which induces difficulties to grow on large scale films with homogeneous thickness and composition. The specific aspect of the crystalline or orientation uniformity has not been investigated, despite its important role on oxide films properties. In this work, the crystalline parameters and the texture of zinc oxide films are studied as a function of position with respect to the central axis of the plasma plume. We demonstrate the existence of large non-uniformities in the films. The stoichiometry, the lattice parameter, and the distribution of crystallites orientations drastically depend on the position with respect to the plume axis, i.e., on the oblique incidence of the ablated species. The origin of these non-uniformities, in particular, the unexpected tilted orientation of the ZnO c-axis may be attributed to the combined effects of the oblique incidence and of the ratio between oxygen and zinc fluxes reaching the surface of the growing film

Ultraviolet degradation of thin films of zinc oxide

Ultraviolet degradation of zinc oxide thin film

Surface acoustic wave/silicon monolithic sensor/processor

A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed

Conductivity phenomena in polycrystalline zinc oxide films

Photoconductivity and electric conductivity of polycrystalline zinc oxide thin film under low intensity irradiatio

Plasma Treatment of Zinc Oxide Thin Film and Temperature Sensing Using the Zinc Oxide Thin Film

Zinc oxide is a direct and wide bandgap, II-VI semiconductor. It has large exciton binding energy, large piezoelectric constant, strong luminescence, and high thermal conductivity. These properties make zinc oxide as a suitable material for various optoelectronic applications. Vacuum based processes of fabrication of zinc oxide thin film dominate the market for their better electrical and optical properties. In this work, zinc oxide thin films were prepared by easy and low cost solution method with oriented crystal growth along (002) plane. To improve electrical and optical property of the fabricated zinc oxide thin films, films were treated with oxygen, hydrogen, and nitrogen plasmas. Oxygen plasma treatment improved the crystallinity of zinc oxide thin film. Hydrogen plasma treatments were found very effective in improving the electrical conductivity of the film sacrificing film’s transmittance. Nitrogen plasma treatment following hydrogen plasma treatment could restore the transmittance maintaining the improved electrical property. Sequential oxygen, hydrogen, and nitrogen plasma treatment decreased the resistivity of zinc oxide thin film by more than two order maintaining transmittance close to the as deposited film. This work also reports a temperature sensor based on the temperature-dependent bandgap of zinc oxide semiconductors. Transmittance measurement of the ZnO films at different temperatures showed sharp absorption edge at around 380 nm and red shift characteristics. An optical temperature sensor was established using the zinc oxide coated glass as sensing element, ultra-violet light emitting diode as light source, and a ultra-violet photodiode as light detector. Short circuit current of the photodiode was measured over a range of the zinc oxide film’s temperature. The short circuit current decreased linearly with the increase of the temperature and the sensitivity was ~0.1 μA/°C

Residual stress and bending strength of ZnO films deposited on polyimide sheet by RF sputtering system

Zinc oxide (ZnO) films were deposited on a soft polyimide sheet substrate by radio frequency sputtering with a ZnO powder target, and the films' crystal orientations and residual stress were investigated using x-ray diffraction as a function of substrate temperature. C-axis oriented ZnO films were achieved using this ZnO powder target method. The ZnO films exhibited high compressive residual stresses between −0.7 and −1.4 GPa. Finally, the authors examined the strength of the obtained film by applying tensile bending loads. No cracks were observed on the surfaces of the ZnO films after a bending test using cylinders with diameters >25 mm. After a bending test using a cylinder with a diameter of 19 mm, large cracks were formed on the films. Therefore, the authors concluded that the tensile bending strength of the obtained films was greater than ∼420 MPa