Preparation of a ZnO Nanostructure as the Anode Material Using RF Magnetron Sputtering System

In this study, a four-inch zinc oxide (ZnO) nanostructure was synthesized using radio frequency (RF) magnetron sputtering to maximize the electrochemical performance of the anode material of a lithium-ion battery. All materials were grown on cleaned p-type silicon (100) wafers with a deposited copper layer inserted at the stage. The chamber of the RF magnetron sputtering system was injected with argon and oxygen gas for the growth of the ZnO films. A hydrogen (H2) reduction process was performed in a plasma enhanced chemical vapor deposition (PECVD) chamber to synthesize the ZnO nanostructure (ZnO NS) through modification of the surface structure of a ZnO film. Field emission scanning electron microscopy and atomic force microscopy were performed to confirm the surface and structural properties of the synthesized ZnO NS, and cyclic voltammetry was used to examine the electrochemical characteristics of the ZnO NS. Based on the Hall measurement, the ZnO NS subjected to H2 reduction had a higher electron mobility and lower resistivity than the ZnO film. The ZnO NS that was subjected to H2 reduction for 5 min and 10 min had average roughness of 3.117 nm and 3.418 nm, respectively.

Studies on Copper Nanometric-Film Deposited by an In-House Developed DC Magnetron Sputtering System

Copper nanofilms are extensively used in the field of material science research. Nanoparticles and nanostructures of copper have various utilities in the field of photocatalytic and sensor applications. The transition metal nanoparticles and nanostructures supply plenty free electrons which drastically enhances the optical and electrical properties compared to bulk material. Here, copper thin films have been deposited on glass slides and silicon substrates using an indigenously developed DC magnetron sputtering system. These depositions have been carried out at three different time spans keeping the magnetron discharge current, working vacuum and target to substrate distance unaltered. The objective of this work is to study the crystalline structure and measure the thickness of the copper nanofilm deposited at three different times. The synthesized films were characterized by using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Secondary Ion Mass Spectrometer (SIMS). Characteristic peaks of copper (111) along with Cu2O (110), (220) and (111) were obtained from the XRD pattern. The average grain size of the deposited films has been calculated using Debye-Scherrer equation. The film thickness ranging from 80-160 nm for various time spans were measured from depth profile analysis using SIMS data.

Fabrication of AlGaN High Frequency Bulk Acoustic Resonator by Reactive RF Magnetron Co-sputtering System

In this study, aluminum gallium nitride (AlGaN) thin films are used as the piezoelectric layers to fabricate solidly mounted resonators (SMR) for high frequency acoustic wave devices. AlGaN film is deposited on a Bragg reflector, composed of three pairs of Mo and SiO2 films, through a reactive radio frequency (RF) magnetron co-sputtering system at room temperature. The optimized deposition parameters of AlGaN film have a sputtering power of 175 W for Al target, sputtering power of 25 W for GaN target, N2 flow ratio (N2/Ar + N2) of 60%, and sputtering pressure of 10 mTorr. The obtained AlGaN film has a smooth surface, uniform crystal grains, and strong c-axis orientation. The contents of Al and Ga in the AlGaN film, analyzed by energy dispersive X-ray spectroscopy (EDS) are 81% and 19%, respectively. Finally, the frequency response S11 of the obtained SMR device shows that the center frequency is 3.60 GHz, the return loss is about −8.62 dB, the electromechanical coupling coefficient (kt2) is 2.33%, the quality factor (Q) value is 96.93 and the figure of merit (FoM) value is 2.26.

Hysteresis effect during reactive sputtering

In this work, we studied the effect of constant parameters of the sputtering system on the width of the hysteresis loop during reactive sputtering. The sticking coefficient of the reactive gas to the surface, the chamber pumping speed, the target area, etc. are taken as parameters. The comparative study was carried out by numerical solution of systems of algebraic equations describing the chemisorption and physicochemical models of metal target reactive sputtering in a single reactive gas. The calculations were performed for sputtering a tantalum target in an Ar + O2 mixture. The studied dependences were non-linear in all cases.

Computer simulation of a power source based on a bipolar pulse shaper for magnetron sputtering systems

The research object is a pulsed bipolar power supply based on a bipolar pulse shaper of increased frequency for magnetron sputtering systems. The research subject is the electrophysical and electromagnetic processes occurring in the bipolar pulse shaper when it is operated with a magnetron sputtering system, as well as the control characteristics. The purpose of the paper is the possibility of creating a pulsed power supply with a power of up to several tens of kW, which makes it possible to increase the stability of the magnetron sputtering system. Besides, the outcomes of computer simulation of a power source based on a bipolar pulse shaper and control algorithm ensuring its stable and reliable operation in association with a magnetron sputtering system are reflected in the paper. The results show that the deviation of the output control characteristics of the bipolar pulse shaper from the analytically obtained characteristics does not exceed 3%. Circuit modeling is carried out in the Swicher CAD/LTspice software package. The mathematical SPICE models of the field-effect STY112N65M5 transistor, transistor IGBT of IRF4PF50WD and STTH8006 diode are taken from the websites of STMicroelectronics and International Rectifier manufacturers.

Effects of Accumulated Energy on Nanoparticle Formation in Pulsed-Laser Dewetting of AgCu Thin Films

Ag50Cu50 films were deposited on glass substrates by a sputtering system. Effects of accumulated energy on nanoparticle formation in pulse-laser dewetting of AgCu films were investigated. The results showed that the properties of the dewetted films were found to be dependent on the magnitude of the energy accumulated in the film. For a low energy accumulation, the two distinct nanoparticles had rice-shaped/Ag60Cu40 and hemispherical/Ag80Cu20. Moreover, the absorption spectra contained two peaks at 700 nm and 500 nm, respectively. By contrast, for a high energy accumulation, the nanoparticles had a consistent composition of Ag60Cu40, a mean diameter of 100 nm and a peak absorption wavelength of 550 nm. Overall, the results suggest that a higher Ag content of the induced nanoparticles causes a blue shift of the absorption spectrum, while a smaller particle size induces a red shift.

Thermal Analysis of Energy Storage Capacity According to Thickness of Nickel/Chromium Alloy Layer

This paper examines a microconstruction consisting of nickel (Ni)/chromium (Cr) alloy thin-film. The total length of the microconstruction was 28 mm, the width was 0.2 mm, and the height was designed to be 1 μm. A thin-film of Ni/Cr alloy was co-sputtered on a silicon dioxide wafer patterned with photoresist via a RF magnetron sputtering system. The RF power ratios applied to the 4 inch target of Ni and Cr were 300 W:100 W (3:1), 300 W:150 W (2:1), and 150 W:150 W (1:1). The electrical resistance of the manufactured microconstruction was calculated and measured through Hall measurements. The temperature generated by applying 1–10 V to the microconstruction electrode was observed by using an infrared camera, and was summarized using a linear equation according to the power applied to each sample.