Sputtering Pressure Research Articles

Investigation of The Effect of High Pressure Sputter Method on Optical Properties of Density Modulated ITO Thin Films

Verimli bir Si-tabanlı güneş hücresi için yüksek geçirgenliğe sahip saydam iletken elektrot kullanmak önemli bir ayrıntıdır. Bu amaçla kullanılan indiyum kalay oksit (İTO) aynı zamanda yansıma önleyici kaplama görevini de yerine getirir. Bu çalışmada, alçak basınç püskürtme (ABP) ve yüksek basınç püskürtme (YBP) yöntemleri ile üretilen farklı malzeme yoğunluklarına sahip iki katmanın bir araya getirilmesi ile oluşturulan yoğunluk modülasyonlu İTO ince filmlerin yansıma önleyici olarak davrandığı ve geçirgenliği düşürdüğü gösterilmiştir. YBP ile elde edilen İTO ince filmin üst tabaka olarak kullanıldığı durumda morfolojisinin daha pürüzlü hale geldiği ve her kalınlık değeri için geçirgenliğin daha yüksek olduğu gözlemlenmiştir. Buna bağlı olarak, bu numunelerde çok yönlü yansımanın daha düşük olduğu gösterilmiştir. YBP-İTO katmanın üzerine sentezlenen nanoyapıların oldukça homojen olması ayrıca bir avantajdır. Sonuç olarak, YBP yöntemi daha kullanışlı bir İTO katmanı üretimi için basit ama etkili bir yöntem olduğunu ispatlamıştır.

Effect of oxygen partial pressure on crystal quality and electrical properties of RF sputtered PZT thin films under the fixed Ar flow and sputtering pressure

Pb(Zr0·52Ti0.48)O3 films have been deposited on Pt/Ti/SiO2/Si (100) substrates by radio frequency (RF) magnetron sputtering method based on a sol-gel derived Pb(Zr0.30,Ti0.70)O3 (PZT) seed layer. Oxygen partial pressure-dependent crystal texture and electrical performance of PZT thin films, under the fixed Ar flow and sputtering pressure during deposition, were investigated. X-ray diffraction (XRD) analysis indicates that the major phase was transformed from perovskite phase containing little pyrochlore phase to pure perovskite phase with increasing oxygen partial pressure during sputtering. Atomic force microscopy (AFM) shows that the film processed by an O2/Ar composition of 10/90 demonstrated a compact and smooth surface. Dense perovskite structure without defects at the interface between seed layer and PZT film was observed utilizing Scanning electron microscope (SEM). Enhanced dielectricity (ε = 920.3, tan δ = 0.02 at 1 kHz) and ferroelectricity (2Pr = 22.8 μCcm−2, 2Ec = 97.9 kV/cm) were generated in the film processed with an O2/Ar composition of 10/90. Moreover, current-voltage (J-V) characteristic was also improved significantly with an O2/Ar composition of 10/90.

Sputtering of Ga-doped ZnO nanocoatings on silicon for piezoelectric transducers

In this study, lead-free, piezoelectric devices were fabricated by vacuum radiofrequency (RF) sputtering of Ga–doped, ZnO (GZO) nanocoatings at different deposition modes on silicon substrates. Several deposition rates were varied (2 to 16 nm/min) by tuning the sputtering voltage and pressure, in order to control the microstructure and surface morphology of the films. The dependences of the piezoelectric properties of GZO thin films on the different deposition conditions were investigated. Significant dependency of the films’ microstructure and surface roughness was observed to the deposition modes used for fabrication. The results showed that after optimization, the surface roughness of the films grown using sputtering voltage 1.1 kV and Ar=2.5.10−2 Torr, is 6 nm. Films with such microstructures are characterized with crystallites orientation (002) and exhibit the highest piezoelectric coefficient of 96.3 pC/m, which is superior compared to other known, lead-free, piezoelectric materials. A simple, membrane–based, vibration sensor was fabricated at the optimal set of conditions to demonstrate the functionality of the coating in a real microelectromechanical (MEMS) device. The working range of the device is between 2 and 800 g and the piezoelectric voltage generated after minimum deformation of 5.4 nm (2g), was 9.66 mV.

Effect of nitrogen flow rate on the properties of nitrogen-doped Cu<sub>2</sub>O

Cuprous oxide (Cu₂O) has the potential applications in photovoltaic and photocatalytic fields. Nitrogen-doping in Cu₂O can improve the conductivity by increasing hole concentration. However, the chemical states of nitrogen in nitrogen-doped Cu₂O have not been studied thoroughly.A series of nitrogen-doped Cu₂O samples are prepared by increasing nitrogen flow rates and simultaneously keeping the sputtering pressure and other parameters unchanged. The samples are characterized by X-ray diffraction (XRD), step instrument, scanning electron microscope (SEM), energy dispersive spectrometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), spectrophotometer and Hall effect et al. The results of Hall effect measurement show that nitrogen-doping can increase the hole concentration by one order of magnitude. The band gap width decreases with the increase of nitrogen flow rate. The nitrogen in Cu₂O is in three forms: β-N (nitrogen atom), α-N₂(molecular nitrogen, —N=N—)and γ-N₂(molecular nitrogen, N≡N). With the increase of nitrogen gas flow rate, the peak of binding energy of β-N increases while that of α-N₂ decreases. The sample prepared at the nitrogen flow rate of 2.0 sccm has the minimum resistivity among all samples.

Functional Data Analysis of Electrical Measurements on Thin-Film Photovoltaic Devices

Cu(In,Ga)Se2 (CIGS)-based photovoltaic cells were fabricated under varying deposition conditions for the Mo back contact and CIGS absorber layers. Specifically, O2 concentration and sputtering pressure were varied during the Mo deposition, as well as the final Mo-layer thickness. The maximum deposition temperature was then varied during the subsequent deposition of the CIGS-layer by thermal coevaporation. The JV response curve of the finished devices were recorded and used to calculate the usual solar performance characteristics (efficiency, J sc, V oc, fill-factor, R oc, and R sc). The effects of the varied fabrication conditions on these characteristics were then investigated, and CIGS-deposition temperature alone was found to have had a significant influence on J sc. Following this, the entire JV -curve was analyzed using functional data analysis (FDA). The curve shape was revealed to be affected not only by temperature, but by O2 conc. and Mo sputter pressure as well. The effect of these fabrication parameters was greatest in regions of the curve larger than V oc. External quantum efficiency measurements on the finished devices were also studied using FDA, indicating a strong influence of temperature in reducing collection across most of the visible spectrum. Mechanisms that aim to explain these observations are proposed. This work details, according to the authors’ best knowledge, the first-ever use of FDA in the analysis of photovoltaic devices.

Self-Supported Nanocolumnar Platinum Thin Film Catalysts for Oxygen Reduction Reaction

Nanocolumnar platinum thin films (Pt-TFs) were produced by high pressure sputtering (HIPS) and investigated as oxygen reduction reaction electrocatalysts for polymer electrolyte membrane fuel cells. Conventional high-density Pt-TF by low pressure sputtering was also studied for comparison. Pt-TFs were deposited on a microporous layer (MPL)-like surface composed of carbon particles in order to mimic the catalyst coated gas diffusion layer in a membrane electrode assembly (MEA). Scanning electron microscopy and transmission electron microscopy images revealed that HIPS Pt-TFs developed a cauliflower-like columnar microstructures, which originated from a shadowing effect. At high working gas pressure conditions of HIPS, sputtered Pt atoms go through several gas phase collisions, lose their directionality, and can arrive at the substrate surface at oblique angles that results in the formation of columnar islands that shadow the gaps among them from incident flux of atoms. This shadowing effect is believed to be enhanced on the rough surface of MPL-like carbon particles that leads to the formation of nano-cauliflower structures. Electrochemical characterization of the samples was performed by cyclic voltammetry and rotating disk electrode measurements on Pt-TF/MPL-like-layer/glassy-carbon-insert samples in aqueous perchloric acid electrolyte. With this approach, we also aimed to relate the catalyst performance obtained by benchtop tests directly to MEA results. Electrochemically active surface area (ECSA) of PT-TFs were found to be ranging from 10 m2/g to 19 m2/g with increasing sputter pressure, which was determined from the charge for hydrogen adsorption and desorption in the cyclic voltammograms. In addition, carbon monoxide (CO)-stripping of Pt-TF coated gas diffusion electrodes were performed in a fuel cell station and similar ECSA values were recorded (ranging from 11 to 15 m2/g). This indicated that successful mimicking of a gas diffusion electrode in an MEA can be achieved by utilizing an MPL-like substrate surface for benchtop tests in aqueous electrolyte environment as opposed to directly depositing Pt-TFs on glassy carbon inserts. Specific activity (SA) values for conventional high-density and nanocolumnar films were similar that was approximately ~600 μA/cm2, which is believed to correspond to grain sizes of >5 nm as obtained from TEM and XRD analysis. On the other hand, mass-specific (MA) activity values increased from 0.06 A/mgPt for conventional Pt-TF to 0.13 A/mgPt for HIPS Pt-TFs. Higher MA agrees with the columnar microstructure of HIPS thin films that increases the surface to volume ratio of the Pt layer that provides a better catalyst utilization compared to conventional Pt-TFs.

The critical role of substrate bias for the sputter deposition of molybdenum thin films

In this study, the critical role of substrate bias during sputter deposition of Mo thin films is discussed. Two sets of Mo thin films having a nominal thickness of 300 nm were prepared at sputtering pressures of 0.55 and 0.33 Pa, with applied negative substrate bias in the range of 0–250 V. While the lateral grain size of ~15 nm was observed for all the Mo films, grain structure, texture, residual stress and resistivity were greatly altered by the combination of bias magnitudes and sputtering pressures. The sputtering pressure of 0.55 Pa in the absence of substrate bias produced substantially high film resistivity of 56.9 μΩ-cm, which can be attributed to the relatively open grain boundary structure formed by the shadow effect for low-mobility Mo atoms. Applied substrate bias reduces the density of open grain boundaries resulting in an abrupt (by more than a factor of two) resistivity reduction to 24.5 μΩ-cm, with the concurrent rise in tensile film stress from 0.2 to 1.3 GPa. The films deposited at 0.33 Pa contain dense grain boundaries and only a modest dependence of film resistivity in the range of 13.8–20.8 μΩ-cm on the substrate bias was observed, for which grain boundary scattering is the dominant scattering mechanism for the resistivity increase relative to the known bulk resistivity. The films deposited at 0.33 Pa possess compressive stress of 0.4 GPa in the absence of substrate bias, which increases up to 2.2 GPa with the applied substrate bias of 250 V.

Study on the performance of titanium film as a diffusion barrier layer for CIGS solar-cell application on stainless-steel substrates

Abstract In this paper, pure titanium (Ti) thin films deposited by radio frequency sputtering were used as a diffusion barrier layer in a flexible copper indium gallium selenium (CIGS) solar cell on a stainless-steel foil and characterized by X-ray diffraction, scanning electron microscopy and second ion mass spectroscopy measurement methods. The influences of the magnetron sputtering pressure on the surface morphology and preferred crystal orientation of Ti films are discussed. It was found that the Ti film showed a (001) preferred orientation and smooth surface topography at lower deposition pressure, while (002) preferred orientation and relatively rough surface topography at higher deposition pressure. In addition, Ti films made with different process pressures were deposited as the barriers and the second ion mass spectroscopy results indicated that a Ti film with the thickness of 200 nm was able to effectively block Fe and Cr diffusion from the stainless-steel foil into the CIGS absorber across the molybdenum back contact. The Ti barrier significantly improved the conversion efficiency of the CIGS solar cell.

Defect generation mechanism in magnetron sputtered metal films on PMMA substrates

Polymer metallization is widely used in a variety of micro and nano system technologies, and magnetron sputtering of a metal film is one of the essential processes of polymer metallization. However, some defects are likely generated in sputtered metal films on a polymer substrate. In this work, the defect generation mechanism in the sputtered Au film on a polymethylmethacrylate (PMMA) substrate was investigated for the first time. The characteristics of defects on the PMMA surface and in the Au film were examined by an optical microscope, a scanning electron microscope (SEM) and a confocal microscope. Detailed characterization results indicate that the ejected Au atoms bombard the PMMA substrate and cause snowflake-like defects on the PMMA surface because of the low hardness of PMMA, then Au atoms nucleate and grow at PMMA defect sites and form a partially suspended metal film, subsequently dropping the photoresist makes the suspended metal film conformally adhere to the PMMA defect, and the snowflake-like morphology is replicated to the metal film. The effects of sputtering parameters on the defects were studied, and the amount of defects in the Au film reduced with the decrease of the sputtering power or the sputtering pressure.

Picosecond laser scribing of bilayer molybdenum thin films on flexible polyimide substrate

Molybdenum (Mo) is a commonly used material as the electrical back contact for Cu(In,Ga)Se2 (CIGS) thin film solar cells taking advantages in electrical, structural and chemical properties. Bilayer structures have been actively examined to achieve Mo films of high conductivity with good substrate adhesion, which will also enable monolithically integrated solar cell modules on flexible platforms by combining laser scribing technology. However, reports on the bilayers on flexible substrates and their scribing by laser are very limited.In this study, we report the characteristics of bilayer Mo films deposited on a flexible polyimide substrate and the impact on the performance of picosecond laser scribing. Bilayer Mo films were deposited over a range of sputtering pressures and discharge powers as well as top-bottom layer thickness ratios, and laser scribing behavior was compared in the practical scribing speed range of the order of m/s. It is shown that microstructural and interfacial characteristics set by top and bottom Mo layers deposition parameters are critical factors influencing laser scribing quality.

Electrochemical and optoelectric behavior of Al-doped ZnO films as transparent anode for Li-ion batteries

Al-doped ZnO (AZO) films were deposited by mid-frequency (MF) sputtering technique as transparent anode materials for Li-ion batteries. The optoelectric and electrochemical behavior of the AZO film were investigated. The high transmittance of 84% in visible range and low electrical resistivity of 7.67 × 10−4 Ω·cm were obtained at sputtering pressure of 0.1 Pa. As a promising anode, the AZO films exhibit high specific capacity of 301 mA h/g. The results reveal that the resistivity of film had great influence on its electrochemical performance. A stable cycling retention was observed due to improved electric conductivity. However, the transparency of AZO film varied to 50% when recharged to 2.5 V, indicating the bleached and colored properties during lithiation/delithiation process. Those characteristics make it a potential candidate for electrochromic devices.

Treatment of a polycarbonate plate for a next-generation vehicle window by radio frequency magnetron plasma sputtering using a PVDF target

A polycarbonate (PC) plate was treated by a radio frequency magnetron sputtering process using a polyvinylidene difluoride target for a next-generation vehicle window. The treated PC surface resulted in a hydrophobic nature at higher sputtering pressures of 50 and 100 Pa, while hydrophilic at a low pressure of 2 Pa. These surfaces were examined with atomic force microscopy (AFM) images and X-ray photoelectron spectroscopy (XPS) analysis. It was found from AFM images that the surface of the films had a smooth structure with roughness Ra of 0.62–0.71 nm for the high pressure, whereas for the low pressure, had an irregular structure with Ra of 2.03 nm. The ratio of the F 1s component to all components of C 1s, O 1s and F 1s from XPS spectra for 100 Pa was approximately seven times higher than that for 2 Pa.

The influence of Ar pressure on the structure and optical properties of non-hydrogenated a-Si thin films grown by rf magnetron sputtering onto room-temperature glass substrates

Seven 1.1–1.4-μm-thick hydrogen-free amorphous‑silicon (a-Si) thin films were deposited at high rates (larger than 10 Å/s), by rf magnetron sputtering (RFMS) onto room-temperature glass substrates. The influence of argon-gas pressure on the structural and optical properties of these amorphous films has been systematically studied. We have used the Wemple-DiDomenico (WD) single-effective-oscillator model, n2(ℏω) − 1 = EdE0/(E02 − (ℏω)2), in order to determine the WD parameters oscillator strength or dispersion energy, Ed, and oscillator energy, E0. The amorphous-to-crystalline mass-density ratio, ρa/ρx, in the empirical expression for Ed, proposed by Wemple, is the key factor in understanding the refractive-index behaviour of the RFMS-a-Si thin films. The value of the static refractive index, n(0), which is related to both the atomic structure and mass density, remains approximately constant up to a threshold Ar-gas pressure of nearly 1 Pa, and then it starts dropping rather abruptly. The decrease found in the Urbach energy, EU, as well as the increase observed in the Tauc gap and slope, Eg and B respectively, for Ar-gas pressures higher than the voided-structure threshold sputtering pressure, clearly suggests that the amount of intermediate-range order present within the RFMS-a-Si layers under study, is increasing in direct response to the increase in the Ar-gas pressure, during the deposition process. This is independently corroborated by the decreasing values of the Raman-intensity ratio, ITA/ITO, as the sputtering pressure increases, in the case of high Ar pressure a-Si films.

On the nano-glass formation of the Ni–Ti thin films and related micro-structure and mechanical properties by controlling sputtering conditions

In this research, glassy Ni–Ti thin films were sputtered on a flexible substrate (Kapton) using direct current (DC) magnetron sputtering system at ambient temperature. The influence of the sputtering pressure on the microstructure, chemical composition, thickness, mechanical properties and the ability to form nano-glass structure was investigated. Micro-structural characterizations of the thin films by x-ray diffraction, scanning and transmission electron microscopy (SEM and TEM) indicate that the sputtered thin films at a minimum pressure of 0.3 Pa have an amorphous structure consisting of nano-glassy grains. Furthermore, as the pressure increasing from 0.1 up to 0.8 Pa, the difference between the chemical composition of the thin films and the target increases. This difference is due to increasing of interatomic collisions between Ar and sputtered atoms that reduces the kinetic energy of sputtered atoms and rises to the scatter of atoms. In addition, the formation of micro-cracks in the films is also encouraged by increasing the sputtering pressure. For evaluation of the mechanical properties of the crystallized Ni–Ti/Kapton composite thin films, the tensile test was used and the results show that the partially crystallized Ni–Ti thin film sputtered at 0.3 Pa has the optimum ultimate tensile strength and toughness due to its composite (amorphous/nano-crystalline) structure.

Evaluation of Nd–Al doped indium-zinc oxide thin-film transistors by a μ-PCD method

In this work, we investigated the effect of deposition conditions such as sputtering power, oxygen ratio and sputtering pressure on the properties of Nd–Al doped indium-zinc oxide (NA-IZO) thin-film transistors based on copper (Cu) electrodes. The quality of deposited films was evaluated by introducing a microwave photoconductivity decay (μ-PCD) measurement. The results showed strong connection between sputtering conditions and μ-PCD results, which reveal that sputtering process was vital for film quality control. In addition, the tendency of obtained Peak value and D value from μ-PCD was in highly consistent with the final devices performance especially the saturation mobility. As a result, the optimized devices showed a saturation mobility of 21.4 cm2 V−1 s−1, threshold voltage about 1.0 V, subthreshold swing about 0.18 V/decade and Ion/Ioff ratio about 9.9 × 107. The non-destructive and efficient μ-PCD method offers a convenient way to optimize the deposition procedure for metal oxide semiconductors.

Effects of Bottom Layer Sputtering Pressures and Annealing Temperatures on the Microstructures, Electrical and Optical Properties of Mo Bilayer Films Deposited by RF/DC Magnetron Sputtering

Most of the molybdenum (Mo) bilayer films are deposited by direct current (DC) magnetron sputtering at the bottom and the top layer (DC/DC). However, the deposition of Mo bilayer film by radio frequency (RF) Mo bottom layer and DC Mo top layer magnetron sputtering has been less studied by researchers. In this paper, the bottom layer of Mo bilayer film was deposited by RF magnetron sputtering to maintain its good adhesion and high reflectance, and the top layer was deposited by DC magnetron sputtering to obtain good conductivity (RF/DC). Generally, the bottom layer sputtering pressure is relatively random, in this paper, the effects of the bottom layer RF sputtering pressures on the microstructures and properties of Mo bilayer films were first studied in detail. Next, in order to further improve their properties, the as-prepared Mo bilayer films at 0.4 Pa bottom layer RF sputtering pressure were annealed at different temperatures and then investigated. Specifically, Mo bilayer films were deposited on soda-lime glass substrates by RF/DC magnetron sputtering at different bottom layer RF sputtering pressures in the range of 0.4–1.2 Pa, the powers of bottom layer RF sputtering and top layer DC sputtering were 120 W and 100 W, respectively. Then, Mo bilayer films, prepared at a bottom layer sputtering pressure of 0.4 Pa and top layer sputtering pressure of 0.3 Pa, were annealed for 30 min at various temperatures in the range of 100–400 °C. The effects of bottom layer sputtering pressures and the annealing temperatures on the microstructures, electrical and optical properties of Mo bilayer films were clarified by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic-force microscopy (AFM), and ultraviolet (UV)-visible spectra, respectively. It is shown that with decreasing bottom layer sputtering pressure from 1.2 to 0.4 Pa and increasing annealing temperature from 100 to 400 °C, the crystallinity, electrical and optical properties of Mo bilayer films were improved correspondingly. The optimized Mo bilayer film was prepared at the top layer sputtering pressure of 0.3 Pa, the bottom layer sputtering pressure of 0.4 Pa and the annealing temperature of 400 °C. The extremely low resistivity of 0.92 × 10−5 Ω.cm was obtained. The photo-conversion efficiency of copper indium gallium selenium (CIGS) solar cell with the optimized Mo bilayer film as electrode was up to as high as 13.5%.

Medical Cyclotron Solid Target Preparation by Ultrathick Film Magnetron Sputtering Deposition

Magnetron sputtering is proposed here as an innovative method for the deposition of a material layer onto an appropriate backing plate for cyclotron solid targets aimed at medical radioisotopes production. In this study, a method to deposit thick, high-density, high-thickness-uniformity, and stress-free films of high adherence to the backing was developed by optimizing the fundamental deposition parameters: sputtering gas pressure, substrate temperature, and using a multilayer deposition mode, as well. This method was proposed to realize Mo-100 and Y-nat solid targets for biomedical cyclotron production of Tc-99m and Zr-89 radionuclides, respectively. The combination of all three optimized sputtering parameters (i.e., 1.63 × 10−2 mbar Ar pressure, 500 °C substrate temperature, and the multilayer mode) allowed us to achieve deposition thickness as high as 100 µm for Mo targets. The 50/70-µm-thick Y targets were instead realized by optimizing the sputtering pressure only (1.36 × 10−2 mbar Ar pressure), without making use of additional substrate heating. These optimized deposition parameters allowed for the production of targets by using different backing materials (e.g., Mo onto copper, sapphire, and synthetic diamond; and Y onto a niobium backing). All target types tested were able to sustain a power density as high as 1 kW/cm2 provided by the proton beam of medical cyclotrons (15.6 MeV for Mo targets and 12.7 MeV for Y targets at up to a 70-µA proton beam current). Both short- and long-time irradiation tests, closer to the real production, have been realized.

High-performance flexible Bi2Te3 films based wearable thermoelectric generator for energy harvesting

The development of wearable thermoelectric generator for human energy harvesting has attracted significant interests in recent years. However, the thermoelectric properties and flexibility of inorganic thermoelectric films still need to be improved. In this study, high-performance flexible Bi2Te3 films with controlled microstructure are prepared on the flexible polyimide substrate by regulating the sputtering pressures, and the power factor can reach 21.7 μW cm−1 K−2. By coating poly (dimethylsiloxane) on the Bi2Te3 surface, the flexibility of the films is improved significantly, so that the change of resistance is kept below 5% after bending 2000 cycles at the radius of 7 mm. Then an in-plane thermoelectric generator containing 13 pairs of thermocouples is fabricated with the open circuit voltage of 48.9 mV and the output power of 693.5 nW at ΔT = 24 K. Meanwhile, the transient open circuit voltage of 12.99 mV is achieved when using the temperature difference between the ambient air and the body, indicating promising application for human energy harvesting.

Non-magnetic interfaces of LaAlO3/SrTiO3 made by on-axis sputter deposition and the contribution of SrTiO3 substrate

Abstract The magnetic properties of interfaces between LaAlO3/SrTiO3 are studied by on-axis sputter deposition at high oxygen pressure. The high pressure sputtering does not induce conductance at these interface, and without conductance, they should not be magnetic either. We find that a possible contribution of SrTiO3 can not be ruled out fully as the bare SrTiO3 substrate also shows a magnetic signal. All interfaces reported in literature grown by either PLD or MBE which are conducting, also have magnetism which arises from the onset of conductivity. If one is missing, the second does too as in the case reported here while SrTiO3 contributes substantially to the conductance of the interface.

Investigation of Rayleigh wave and Love wave modes in [formula omitted] ZnO film based multilayer structure

Piezoelectric ZnO film-based multilayer structures with versatile surface acoustic wave (SAW) modes are promising for use in the cutting-edge lab-on-chip-level bio-sensing applications which are desired to integrate sensing and microfluidics functions on the same miniature chip. This paper investigates a multilayer structure of SiO2/ZnO112¯0/r-sapphire with the feasibility of Rayleigh and Love wave modes along the two orthogonal directions. Theoretical calculations are performed to analyze different SAW modes and to optimize the structure parameters accordingly. ZnO is prepared by magnetron sputtering and its optimal fabrication parameters of sputtering pressure of 0.2 Pa, pure oxygen ambient gas and substrate temperature (500 °C) are determined towards the preferred 112¯0 orientation. The crystallographic characteristics and surface morphology of the fabricated ZnO film are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface vibration trajectory of the two modes both are measured using a laser vibrometer. It is verified the SAW mode parallel to the c-axis (0002) is a Rayleigh wave while that along 11¯00 is an SH-SAW/Love wave. As the SAWs encounter a PDMS cell filled with water on the film surface, the Love wave shows an insignificant acoustic damping of less than 2 dB and a reliable transmission response is maintained. In contrast, the acoustic energy of the Rayleigh wave based devices mostly radiates into liquid accompanied by an insertion loss of 13 dB and leading to obvious streaming.