Papers by Keyword: RF Sputtering

Abstract: 82% Ni-Fe films have been prepared using Radio frequency (R.F) sputtered, R.F induced substrate bias. The results presented are of study of sputter films deposition at various RF substrate bias conditions so that suitable sputtering rate with optimum (target) composition could be determined for magnetoresistive sensing applications. Films have been sputtered with substrate temperature of 200^° C, sputter gas (argon) pressure of 10mTorr with film thicknesses near 1000 ^°A. Substrate bias potential in the range 0 V to -400 V is varied in order to determine its dependence upon film composition and deposition rate. The result presented indicates the strong bias dependence upon film composition and deposition rate with most useful films for the application in concern could be produced at substrate bias potential in the range of -80 V to -120 V.

Abstract: This study utilizes tungsten oxide as the research subject and investigates changes between different argon/oxygen gas flow ratio and deposits on ITO substrates through RF reactively sputtering. Propylene carbonate (PC) is further mixed with LiClO₄ for the preparation of electrolyte. After packaged into components, electric voltage is applied to the films to generate reduction or oxidization, which can obtain different colored/bleached states. Lastly, Raman spectroscopy analysis is performed to get a greater understanding of electrochromic mechanisms. The results of the experiment discovered that as-deposited tungsten oxide thin film shows the formation of W⁺⁶ states, and the application of driving voltage causes the formation of W+5 states. At the same time, the thin film coloring effect appears. Increases in driving voltage cause the gradual conversion of W^{+ 6} states into W⁺⁵ states, which further leads to a more significant coloring effect. On the other hand, W-O-W deformed crystal lattice structures are also produced, which also affects the incidence of electrochromic property.

Abstract: Sr_0.6Ba_0.4Nb₂O₆ (SBN) thin films were prepared by radio frequency (RF) sputtering onto the SiO₂/Si/Al and Pt/Ti/Si substrates to form the MFIS and MFM structures. Their deposition rates increased with decreasing oxygen concentration and with increasing RF power. Their optimal deposition parameters were the substrate temperature of 500°C, chamber pressure of 10 mTorr, oxygen concentration of 40%, and RF power of 120W, respectively. The rapid temperature annealing (RTA) process had large effects on the grain growth of the SBN thin films. The effects of different RTA temperatures on the leakage current density - electrical field curves and the capacitance - voltage curves of the SBN thin films were also investigated.

Abstract: In this study, the physical, electrical, and structural parameter on radio frequency (RF) sputtered molybdenum thin film is investigated as a function of two deposition parameters: rf power, and argon (Ar) pressure. Films are sputtered onto the substrates nominally held in room temperature in a RF sputtering system at partial argon (Ar) pressure. A number of 10 films are deposited at 8 sccm of Ar pressure while varying the rf power from 90 to 360 watt. Besides, another set of 7 films are deposited at 240 watt RF power while varying the Ar pressure from 8 to 32 watts. All the films are characterized using FESEM, AFM, XRD, and four points probe. The analysis results substantiate that, to fabricate a low resistive thin layer of molybdenum (Mo) both sputtering power, and deposition time Ar pressure plays significant rules. It is found that, with the increase of the RF power (90 to 280 watt) the deposition rate increase from 1.2 A⁰/sec to 4.4 A⁰/sec. But at a RF power higher than 280 watt the deposition rate saturated and it does not increase as linear as before. Also resistivity continuously decreases as the RF power increases from 90 watt up to 270 watt, after that the resistivity remain almost same regardless the RF power increased. Besides, by varying the Ar pressure it is found that with the increase of the Ar pressure the deposition rate increase until 20 sccm (up to 2.4 A⁰/sec). With further increase of the Ar pressure deposition rate start reducing and reached 2.1 A⁰/sec at 32 sccm. Based on the above investigation and analysis optimized film is deposited and further analyzed. The surface roughness is analyzed using AFM characterization tool and found 27.4519 nm. The FESEM and XRD analysis along with the resistivity of the film is used to measure the strain of the deposited film and found a strain of less than 0.01% on the optimized film, which is essential for MEMS/NEMS device fabrication and energy harvesting applications.

Abstract: TiO_2, transition metal oxide nanotubes were successfully grown by anodizing of titanium foil (Ti) in ethylene glycol electrolyte containing 5wt % hydrogen peroxide and 5wt % ammonium fluoride for 60 minutes at 60V. It was found such electrochemical condition resulted in the formation of nanotube with average diameter of 90nm and length of 6.6 µm. These samples were used to study the effect of W loading by RF sputtering on TiO₂ nanotubes. Amorphous TiO₂ nanotube substrate leads to enhance incorporation of W instead of anatase. Therefore for the entire study, W was sputtered on amorphous TiO₂ nanotube substrate. TiO₂ nanotube sputtered below 1 minute resulted in the formation of W-O-Ti while beyond this point; it accumulates to form a self-independent structure of WO₃ on the surface of the nanotubes. TiO₂ nanotube sputtered for 1minute at 100W and annealed at 450°C exhibited best photocurrent density (1.4 mA/cm²) with photoconversion efficiency of 2.5%. The reason for such behavior is attributed to W⁶⁺ ions allows for electron traps that suppress electron-hole recombination and exploit the lower band gap of material to produce a water splitting process by increasing the charge separation and extending the energy range of photoexcitation for the system.

Abstract: Nickel films of varying thicknesses between 70 and 300 nm were deposited on glass substrates by RF sputtering and their broad (111) FCC peaks were identified by X-ray diffraction. The surface roughness and sub-micron grains were revealed by scanning electron microscopy. According to vibrating sample magnetometry, the films showed hysteresis loops with comparable coercive field and saturation field for the in-plane and perpendicular magnetizations. The increase in thickness substantially increased the magnetization and the squareness of the Ni films. The thickness can be classified into 2 regimes by the variation of squareness. The films are thinner than 200 nm showed the in-plane anisotropy whereas the perpendicular anisotropy was developed in the case of the thickness above 200 nm.

Abstract: Abstract. A new technique of inductive measure to determine the initial magnetic permeability (r) of Yttrium Iron Garnet (YIG) thin films has been conceived and developed in our laboratory. The magnetic material is deposited by radio-frequency sputtering between two copper thin layers on alumina substrate. Because the as-deposited films are amorphous and non magnetic, thermal annealing is necessary to make the films crystallize and to obtain satisfactory magnetic properties. After different tests considering the geometrical, morphological and magnetic properties, we have established a protocol permitting to manufacture a prototype in an original design. The performance of the fabricated micro-inductor has been checked using a physical-chemistry characterization. To obtain accurate measurements, we have used a four-point probe test bench and a precision LCR meter. The current sheet method has been validated with thick layers of commercial YIG. The results obtained for thick and thin films of YIG have been compared to the simulation and theoretical ones. Several tests, made for different thickness and different number of loops, have permitted us to evaluate the magnetic permeability of YIG thin films to 32 ± 4.

Abstract: The NiOx thin flims deposited on SnO2/glass substrates by RF sputtering were investigated through XRD、SEM、spectrophotometer and Cyclic voltammetry. The relationship between electrochromic properties and micro-structure of NiOx was also studied. Results show that NiOx films prepared by sputtering are preferred to grow along (200) direction; the crystallize size of NiOx films increases and the transmittance of colored and bleached states of NiOx films also increases with annealing temperature rising, but the transmittance different between bleached and coloured states reduces. The declined electrochromic propertiey of NiOx with the increase of annealing temperature is also found.

Abstract: The paper describes results of investigation on sputtered NiFe Films to determine the sputter deposition condition that could produce magnetic field sensors with the desired magnetic and magnetoresistive properties. The magnetic thin films materials used in such devices should have a low coercive force, a low anisotropy field and low magnetization dispersion, α50 with high magnetoresistance ratio. From the results presented, it is shown that that the most useful films for 82%Ni-Fe composition are produced at 200 °C-250 °C moderate substrate temperatures. It is also possible to specify the substrate bias potential and sputter gas pressure sputter deposition conditions under which the 82%Ni-Fe thin films may be employed for the production of magnetoresistine sensors with near optimum magnetic and magnetoresistive properties. The work also provide understanding of the effects on the magnetic properties of sputtered magnetic films that is very limited as current literature is almost entirely limited to evaporated magnetic films.

Abstract: Lead-free potassium sodium niobate ceramic thin films were synthesized using rf magnetron sputtering technology for MFIS structures. The optimal sputtering parameters of the as-deposited KNN thin films for depositing times of 1h were obtained. Regarding the measured physical properties, the micro-structure and thickness of as-deposited KNN thin films for different oxygen concentration were obtained and compared by XRD patterns and SEM images. The surface roughness of KNN thin film was also observed by AFM morphology. The average grain size and root mean square roughness were 250 and 7.04 nm, respectively. For KNN thin films in the MFIS structure, the capacitance and leakage current density were 280 pF and 10^-8A/cm², respectively. We investigated that the leakage current density and the memory window increased, the capacitance critically increased as the oxygen concentration increased from 0 to 40%. However, the excess oxygen concentration process was decreased the electrical and physical of as-deposited KNN thin film. The effect of oxygen concentration on the physical and electrical characteristics of KNN thin films was investigated and determined.