Oxygen Gas Flow Ratio Research Articles

The investigation of preferred orientation growth of ZnO films on the PbTiO 3-based ceramics and its application for SAW devices

Poly-crystal ZnO films with c-axis (0 0 2) orientation have been successfully grown on the lead-based ceramic substrates by RF magnetron sputtering technique. The deposited films were characterized as a function of deposition time, argon–oxygen gas flow ratio, and RF power. Crystalline structures of the films were investigated by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Highly oriented films with c-axis normal to the substrates can be obtained by depositing under a total pressure of 10 mTorr containing 50% argon and 50% oxygen and RF power of 70 W for 3 h. The phase velocity, electromechanical coupling coefficient and temperature coefficient of frequency of surface acoustic wave (SAW) device with ZnO/IDT/PT-ceramic structure were investigated. It shows that the preferred oriented ZnO film is beneficial for improving the electromechanical coupling coefficient of SAW device.

Correlation between the microstructures and the cycling performance of RuO2 electrodes for thin-film microsupercapacitors

We have fabricated all solid-state thin-film microsupercapacitors (TFSCs) using RuO2 electrodes and LiPON electrolytes. The RuO2 electrodes were grown at oxygen gas flow ratios [O2/(O2+Ar)] of 10% and 30%. Room-temperature charge–discharge measurements show that specific capacitance is dependent on the oxygen gas flow ratio. Glancing angle x-ray diffraction (GXRD) and transmission electron microscopy (TEM) results show that the RuO2 electrodes grown at 10% contain nanocrystallites (0.7–10 nm across) embedded in the amorphous matrix, while the electrodes grown at 30% are polycrystalline (with grains of 0.7–15 nm in diameter). Based on the GXRD, TEM, Auger electron spectroscopy depth profile, and scanning electron microscopy results, the oxygen flow ratio dependence of the cycling performance of the RuO2-based TFSCs are discussed in terms of the combined effects of the microstructures of the electrodes, interfacial products, and the surface morphology of the electrodes.

Physical and structural properties of ZnO sputtered films

In this paper, poly-crystal zinc oxide (ZnO) films with c-axis (002) orientation have been successfully grown on the silicon substrate by r.f. magnetron sputtering technique. The deposited films were characterized as a function of deposition temperature, argon–oxygen gas flow ratio, and r.f. power. Crystalline structures, stress and roughness characteristics of the films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurement. By controlling deposition parameters and annealing temperature, we could improve intrinsic stress and surface roughness of ZnO film. Preferred deposition condition was found to show good film quality for SAW device applications.

Electrical Properties of Amorphous Rh Oxide Thin Films Prepared by Reactive Sputtering

Conducting Rh oxide thin films were prepared by sputtering a Rh target in an Ar and O2 mixed gas. Effects of the oxygen gas flow ratio on the crystallinity, chemical bonding state and resistivity were studied. Amorphous Rh2O3 films were prepared at an O2 flow ratio of 20%. The Rh2O3 films had a relatively high resistivity of 2 mΩcm and a negative temperature coefficient of resistance (TCR) of -1000 ppm/°C, which indicated semiconducting characteristics. On the other hand, amorphous RhOx films with a composition of 1.5 ≤x ≤1.7 were prepared at O2 flow ratios above 40%. Resistivity of these RhOx films were 800 µΩcm and had almost no temperature dependence. Metallic conduction characteristics of RhO2 were assumed to be revealed by the decrease in the oxygen deficiency.

Stoichiometry dependency of the firing and sustain voltage properties of MgO thin films for alternating current plasma display panels

MgO thin films were prepared on soda-lime glass substrates by the radio frequency magnetron sputtering using a MgO target at various oxygen gas flow ratios [O2/(Ar+O2)] in order to understand the relationship between MgO film properties and discharge characteristics. The gas discharge property of alternating current plasma display panels (ac PDP) was found to strongly depend on the crystallinity, surface morphology, and contamination with hydroxyl groups, as well as film stoichiometry. The MgO films had a tendency to form structures with a preferred growth orientation of (200) planes with an increasing oxygen gas flow ratio [O2/(Ar+O2)] to 0.1. The MgO films were also observed to be fully stoichiometric at an oxygen gas flow ratio [O2/(Ar+O2)] of 0.1. The fully stoichiometric MgO films were found to have a minimum in surface roughness and amount of hydroxyl groups and a maximum in grain size. The ac PDP with fully stoichiometric MgO films also showed lower firing and sustaining voltages than those with either magnesium-rich or oxygen-rich MgO films. This was largely attributed to the larger grain size and the reduced hydroxyl groups in the films.

Plasma enhanced chemical vapour deposition of SiO xN y in an integrated distributed electron cyclotron resonance reactor

The deposition of silicon alloy thin films at room temperature is of increasing interest for various applications, such as functional, protective and optical coatings on polymers. In this work an integrated distributed electron cyclotron resonance (IDECR) high density plasma reactor is used for the deposition of SiO x N y thin films with variable optical properties. The reactor has planar geometry and is scalable for large area applications. Properties of material are analyzed with in situ UV–Visible ellipsometry, ex situ infrared transmission, RBS and ERDA measurements. Without substrate heating, dense, non-absorbing and low hydrogen content stoichiometric films of SiO 2 and Si 3N 4 are grown from the mixture of SiH 4, O 2 and N 2. Deposition rates are between 0.5 and 5 nm/s for Si 3N 4 and SiO 2, respectively. By changing the nitrogen to oxygen gas flow ratio the refractive index (measured at 632.8 nm) can be smoothly and reproducibly tuned from 1.96 to 1.46. The correlation between material properties and plasma parameters indicates that the silane partial pressure influences the hydrogen incorporation into the silicon nitride films.