Sputtering Power Research Articles

Interfacial engineering strategy and controlled growth of MoSe2@ZnO composite material and its light-matter coupling

The combination of metal oxides and two-dimensional materials can effectively separate photogenerated electron-hole pairs under photoexcitation conditions, which can solve the problems of low carrier mobility and easy agglomeration of two-dimensional materials. Herein, the MoSe2 loaded with ZnO (MoSe2@ZnO) was prepared by two-step hydrothermal and magnetron sputteringmethod. The results of scanning electron microscopy and transmission electron microscopy show that the MoSe2 and MoSe2@ZnO composite material with controllable size are successfully prepared, and the agglomeration problem of the MoSe2 is solved. The results of X-ray photoelectron spectroscopy show that the electrons at the Fermi level of MoSe2 can be transferred to the Fermi level of ZnO to form a built-in electric field. When Fermi level of MoSe2 and ZnO reaches the same position, the band bending can be caused, which can inhibit the recombination of photogenerated electron-hole pairs and enhance the carrier mobility. The Z-scan results show that MoSe2 has nonlinear absorption coefficient of ∼10−7 cm/W, and the reverse saturation absorption characteristics of MoSe2 can be effectively improved by controlling the sputtering power The results show that MoSe2@ZnO has excellent photoelectric properties, so it has broad research prospects in optoelectronic devices and other development fields.

Microstructure, mechanical properties and tribological behaviors of gold coating determined by surface quality

Gold-plated electrical contacts have been widely applied in engineering due to their excellent features and the ever-growing interest in microelectronic products. However, gold coatings have extremely low hardness and load-bearing capacity, limiting their reliability, wear resistance and lifespan. This study deposited gold coatings on the surface of electrical contacts by employing magnetron sputtering at varying powers. The effects of sputtering power on the microstructure, mechanical properties and wear resistance of coatings were elaborated using the growth mode and wear theory. The results show that increasing the sputtering power from 100 to 500 W enhances the densification, crystallinity, and (111) preferred orientation of the gold coating, resulting in improved adhesion strength, mechanical properties, and tribological behaviors. This study proposed the reasons for the outstanding properties of the coatings, along with theoretical analysis and experimental results.

Research on the possibility of controlling the growth of thin copper layers deposited by DC magnetron sputtering

This paper addresses the influence of the sputtering time and hence thickness of thin copper (Cu) layers on the grain size, surface morphology and electrical properties. Cu layers 54–853 nm thick were deposited by DC magnetron sputtering at room temperature from a Cu target with a sputtering power of 2.07 W × cm−2 in an argon atmosphere at a pressure of 8 × 10−3 mbar. The structural and electrical properties were determined on the basis of four-contact probe measurements, stylus profilometry, atomic force microscopy (AFM), scanning electron microscopy (SEM) with an X-ray microanalysis (EDS) detector, and X-ray diffraction (XRD). The results of the conducted experiments show that the structure of thin copper layers can significantly change depending on the thickness and deposition process parameters. Three characteristic areas of structural changes and growth of copper crystallites/grains were distinguished. Ra and the RMS roughness linearly increase with increasing film thickness, while the crystallite size significantly changes only for copper films thicker than 600 nm. In addition, the resistivity of the Cu film is reduced to approximately 2 μΩ × cm for films with a thickness on the order of 400 nm, and a further increase in their thickness does not have a significant effect on their resistivity. This paper also determines the bulk resistance for the Cu layers under study and estimates the reflection coefficient at the grain boundaries.

Synthesis of Al Thin Films with High Optical Transmittance by DC Magnetron Sputtering Process Parameter Optimization

Nanostructured Al thin film with higher optical transmittance and electrical conductivity has intensive applications in solar cells and optical and microelectronic devices. This experimental-based research study has optimized the DC magnetron sputtering deposition parameters (sputtering power, sputtering current, voltage, and working gas pressure) for Al thin film deposition to obtain the highest optical transmittance and lower sheet resistance. Optical transmittance, surface roughness, film thickness, sheet resistance, grain size, and surface morphology were characterized using UV-vis-NIR spectroscopy, surface profiler, spectroscopic ellipsometry, four-point probe, and FE-SEM, respectively to determine the effects of sputtering process parameters on Al films’ different properties. Experimental investigations reveal that electrical conductivity, surface roughness, grain size, and deposition rate increase with increasing of sputtering power at certain working gas pressure. At the optimized condition (sputtering power 80 W, working gas pressure 5 mTorr, deposition time 5 min and ambient temperature), the relatively higher optical transmittance in visible region 96%, moderate sheet resistance 0.196 ohm/square and lowest average surface roughness 2.86 nm were obtained for Al thin film. After all, this research study will help to understand the best Al film deposition parameters in terms of optical transmittance and electrical conductivity for future research and industrial applications.

High-Entropy Alloy Films

High-entropy alloy films have the same excellent properties as high-entropy alloys and can better realize the practical applications of high-entropy alloys. This paper takes the high-entropy alloy films as the object of discussion. The preparation process, microstructure, hardness, wear resistance and corrosion resistance of high-entropy alloy films are mainly discussed and the influence of nitridation, sputtering power, substrate temperature, substrate bias and other factors on the phase structure of alloy films is analyzed. High-entropy alloy films can be prepared using magnetron sputtering, laser cladding, pulsed laser deposition, detonation spraying, electrochemical deposition and other processes. High-entropy alloy films tend to form a solid solution and amorphous state, and their hardness is far higher than that of traditional films. Among them, the hardness of high-entropy alloy nitride films can reach the standard of superhard films. Wear resistance is usually proportional to hardness. Due to the corrosion-resistant elements and amorphous structure, some high-entropy alloy films have better corrosion resistance than stainless steel. High-entropy alloy films have shown profound development prospects in the fields of wear-resistant coatings for tools, corrosion protection, diffusion barrier and photothermal conversion coatings.

Electrical and optical properties of nanocrystalline ZnSnN2

The electron density of ZnSnN2 prepared in many experiments is as high as 1019 cm−3 and it is challenging to prepare ZnSnN2 with electron density of 1016 cm−3. Here it is shown that nanocrystalline ZnSnN2 with electron density of 1016 cm−3 can be deposited with sputtering an alloy target at relatively lower sputtering power and substrate temperature. The structural, electrical and optical properties of nanocrystalline ZnSnN2 are studied. The effect of annealing on the properties of nanocrystalline ZnSnN2 with electron density of 1016 cm−3 is also investigated. The results show that the electron density of ZnSnN2 remains to be 1016 cm−3 after being annealed at 300 °C.

Combined Effect of Substrate Temperature and Sputtering Power on Phase Evolution and Mechanical Properties of Ta Hard Coatings

Ta hard coatings were prepared on PCrNi1MoA steel substrates by direct current magnetron sputtering, and their growth and phase evolution could be controlled by adjusting the substrate temperature (Tsub) and sputtering power (Pspu) at various conditions (Tsub = 200–400 °C, Pspu = 100–175 W). The combined effect of Tsub and Pspu on the crystalline phase, surface morphology, and mechanical properties of the coatings was investigated. It was found that higher Pspu was required in order to obtain α-Ta coatings when the coatings are deposited at lower Tsub, and vice versa, because the deposition energy (controlled by Tsub and Pspu simultaneously) within a certain range was necessary. At the optimum Tsub with the corresponding Pspu of 200 °C-175 W, 300 °C-150 W, and 400 °C-100 W, respectively, the single-phased and homogeneous α-Ta coatings were obtained. Moreover, the α-Ta coating deposited at Tsub-Pspu of 400 °C-100 W showed a denser surface and a finer grain, and as a result exhibited higher hardness (9 GPa), better toughness, and larger adhesion (18.46 N).

Crystalline phase control of BiVO4 thin films using RF sputtering

A selective fabrication method for monoclinic-scheelite (m-s) BiVO4 and tetragonal-zircon (t-z) BiVO4 thin films using radio fRequency (RF) sputtering from a single target was developed. The kinetic energy of the sputtered atoms was controlled by varying the sputtering power to obtain BiVO4 films with m-s and t-z crystalline phases. Although the band gap of the t-z BiVO4 phase (3.0 eV) was larger than that of m-s BiVO4 (2.5 eV), the deposited t-z BiVO4 films showed a comparable photocurrent density (1.5 mA cm−2) at 1.23 V versus the reversible hydrogen electrode (400 W Xe lamp). This was mainly because of the reduced sputtering damage in the t-z BiVO4 crystal, which originated from the low sputtering power as well as the deep valence-band position in t-z BiVO4 that enabled the efficient utilization of the photocarriers. This work provides insights into crystalline phase control using the particle kinetic energy in sputtering.

Development of photocatalytic nanostructured TiO2 and NiO/TiO2 coatings by DC magnetron sputtering for photocatalytic applications

High photocatalytic activity layers were obtained by combining a TiO2 nanostructured coating support with 10 nm and 20 nm NiO layers synthesized by direct current (DC) magnetron sputtering. In order to improve the TiO2 crystallinity several sputtering process parameters were studied. The TiO2 and NiO/TiO2 coatings were characterized through XPS, XRD, FESEM, AFM and UV transmittance measurements, in the latter case, for band gap determination. The photocatalytic activity of the coatings was tested through methylene blue degradation under UV light. The formation of a p-n heterojunction between the TiO2 and NiO layers improved the degradation rates, compared to the bare TiO2 layers; however, almost no difference can be seen when increasing the NiO sputtering power and subsequently the coating thickness to higher values than 20 nm.

A Self-Crystallized Nanofibrous Ni-GDC Anode by Magnetron Sputtering for Low-Temperature Solid Oxide Fuel Cells.

The optimum composition ratio of the anode cermet (Ni-GDC) for solid oxide fuel cells (SOFCs) varies because the electron-collecting mechanism is different depending on its applications. A Co-sputtering method facilitates ratio control with sputtering power adjustment. However, there is a practical issue with fabricating anode cermet with various ratios attributed to the large sputtering yield gap of the metal target, Ni, and the ceramic target, gadolinia-doped ceria (GDC). Therefore, in this study, a Gd-Ce metal alloy was applied instead of GDC to match the sputtering rate with that of Ni, which enables a wide ratio range achievement. A thin film of Gd-Ce oxidized after deposition and successfully transformed to crystallized GDC under a SOFC operation environment. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirmed its crystallinity, and the film deposited with various power ratios was sputtered on the ScSZ electrolyte pellet to clarify the optimum Ni-GDC ratio for thin-film SOFCs. Last, the Ni-GDC was applied to anodized aluminum oxide (AAO)-supported SOFCs to maximize the performance. The performance change according to the thickness of Ni-GDC was identified, and the best performance among them was 638 mW/cm2 at 500 °C.

Conductometric ethanol gas sensor based on a bilayer film consisting of SnO2 film and SnO2/ZnSnO3 porous film prepared by magnetron sputtering

As one important type of the sensing material, the metal oxide film can realize accurate detection to the low concentration of ethanol. In this paper, a double-layer nano film was prepared by sputtering a SnO2 bottom layer and co-sputtering a SnO2/ZnSnO3 porous top layer with SnO2 and ZnO targets. Firstly, the effects of Zn content on the properties of the single-layer SnO2/ZnSnO3 porous film were investigated by changing sputtering power of ZnO and keep sputtering power of SnO2 constant. When the sputtering power of ZnO is 25 W, the single-layer SnO2/ZnSnO3 porous film has the best response to ethanol. To expose more adsorption sites to air, the SnO2/ZnSnO3 porous layer was deposited on a SnO2 thin film with thickness of 10 nm to form the double-layer sensing material. The double-layer thin film has response of 11.5–50 ppm ethanol at 290 °C, which is 2.1 times that of the single-layer SnO2/ZnSnO3 porous layer, and the response and recovery time of the double layer are 56 s and 666 s to 50 ppm ethanol at 290 °C, which are shortened by 63 s and 641 s compared to those of the single layer, respectively. In addition, the double-layer porous film also exhibits excellent long-term stability and good selectivity to ethanol. The n-n heterojunction formed between SnO2 and ZnSnO3 and unique double-layer porous structure are the main reasons for the excellent sensing performance.

Magnetic and structural properties of sputtered thick Co2FeSi alloy films

We investigate magnetic and structural properties of the sputtered thick Co2FeSi (CFS) alloy films. X-ray diffraction measurements show CFS alloy film changes from amorphous to disordered A2 structures after annealing, which leads to pronounced increase in saturation magnetization. For the as-deposited films in-plane uniaxial magnetic anisotropy is determined to be in the range of 103–104 erg/cm3, showing strongly dependent to film thickness. After annealing a fourfold cubic magnetic anisotropy is witnessed. Structural ordering is observed to improve with increasing film thickness. Similiar trend of the magnetic anisotropy with sputtering power is witnessed, which can be explained by equivalent annealing effect of the high-power sputtering. Our results show that magnetic anisotropy properties of the CFS alloy films are strongly dependent to film thickness and structural ordering, tuned by anealing tempeature and sputtering power. These findings may be helpful for designing Co2FeSi-based spintronic devices.

Interface Design of 3D Flower-like Ag@ZnSe Composites: SERS and Photocatalytic Performance

In this work, we cosputtered Ag and ZnSe on a polystyrene template to form a three-dimensional (3D) Ag@ZnSe (x) structure. The 3D surface morphology and material composition that provided abundant "hot spots" were controlled by adjusting the sputtering power of the ZnSe, which was confirmed by finite-difference time-domain (FDTD) simulation. The introduction of ZnSe into the noble metal Ag also introduced a charge-transfer (CT) effect into the system, and the CT path was proven with the two-dimensional correlation spectroscopy (2D-COS)-surface-enhanced Raman scattering (SERS) technique. In addition, the substrate exhibited excellent catalytic activity due to the CT effect. The catalyzed degradation of malachite green (MG) was due to the CT effect in the system, and the catalytic process was successfully monitored by in situ SERS. Most importantly, the catalytic degradation by Ag@ZnSe (x) with different parameters was proportional to the degree of CT (ρCT). The SERS and catalytic mechanisms were analyzed in depth with the 2D-COS-SERS technique, which was also useful in verifying the CT process. The catalytic sites for MG were successfully monitored with the 2D-COS-SERS technique. This study provides a reference for studies of the synergistic effects of the electromagnetic mechanism and CT, as well as a new perspective on photocatalysis with dye molecules and monitoring of the catalytic processes.

Effect of Cu2O Sputtering Power Variation on the Characteristics of Radio Frequency Sputtered p-Type Delafossite CuCrO2 Thin Films

For the first time, the effect of Cuprous Oxide (Cu2O) sputtering power variation on the radio frequency sputtered Copper Chromium Oxide (CuCrO2) thin films was studied. In this work, the sputtering power of Cr2O3 was held constant at 200 W while the sputtering power of the Cu2O target was varied from 10 to 100 W. The films were subsequently annealed at 650 °C in N2 ambiance. The effects of Cu2O sputtering power variation on the structural, optical, and electrical properties of the films have been reported in this work. X-ray diffractometer (XRD) study revealed that the single-phase delafossite structure of CuCrO2 was only obtained at Cu2O sputtering power of 50 W. X-ray photoelectron spectroscopy (XPS) analysis further established the results of XRD study where Cu in 1+ oxidation state was identified in thin films obtained at 50 W of Cu2O sputtering power. The optical studies were conducted in this work on all the post-deposition annealed films in the wavelength range of 200–800 nm. The energy dispersive x-ray spectroscopy (EDS) study revealed a near stoichiometric composition ratio of 1:1.06 of Cu:Cr at% obtained in the films sputtered with 50 W of Cu2O sputtering power. The highest optical transmission of ~81% and the highest optical bandgap of 3.21 eV were observed for single-phase CuCrO2 thin films. The optical transmission and the optical bandgap were found to decrease with an increase in the Cu2O sputtering power. The electrical study performed on all the post-deposition annealed films revealed that the lowest resistivity of 0.652 Ω-cm was identified for single-phase CuCrO2 thin films obtained at 50 W of Cu2O sputtering power.

Manipulation of the Martensitic Transformation and Exchange Bias Effect in the Ni45Co5Mn37In13 Ferromagnetic Shape Memory Alloy Films

The martensitic phase transition and exchange bias effect of the Ni-Mn-based ferromagnetic shape memory alloys (FSMAs) Ni45Co5Mn37In13 (Ni-Co-Mn-In) films are investigated in this paper. The martensitic transformation properties of the Ni-Co-Mn-In alloy target material are manipulated by the process of electric arc melting, melt-fast quenching, and high-temperature thermal pressure. The Ni-Co-Mn-In alloy films with martensite phase transition characteristics are obtained by adjusting deposition parameters on the (001) MgO substrate, which shows a significant exchange bias (EB) effect at different temperatures. With increasing sputtering power and time, the film thickness increases, resulting in a gradual relaxation of the constraints at the interface between the film and the substrate (the interfacial strain decreases as the increase of thin film thickness), which promotes the martensite phase transition. Between zero-field cooling (ZFC) and field-cooled (FC) curve obvious division zone, the decrease of exchange bias field (HEB) and coercive force field (Hc) with an increase in test temperature is due to ferromagnetic (FM) interaction begins to dominate, resulting in a reduction of antiferromagnetic (AFM) anisotropy at the interface. The maximal HEB and Hc reach ~465.7 Oe and ~306.9 Oe at 5 K, respectively. The manipulation of the martensitic transformation and EB effect of the Ni-Co-Mn-In alloy films demonstrates potential application in the field of information and spintronics.

Tuning microstructure and mechanical and wear resistance of ZrNbTiMo refractory high-entropy alloy films via sputtering power

Introduction: Recently, great efforts have been dedicated to tailoring the microstructure of the RHEA films to further optimize the performance of the films. However, there is still a lack of in-depth study on their wear mechanism and microstructure evolution.Methods: In this work, the novel ZrNbTiMo RHEA films were prepared by DC magnetron sputtering and splicing target techniques. The effects of sputtering power on the microstructure, hardness, toughness, and wear resistance of ZrNbTiMo RHEA films were investigated in detail.Results: The ZrNbTiMo films possess the nanocomposite structure, the bcc nanocrystal is wrapped in an amorphous phase. The wear resistance of the film is expected to be improved by finding an appropriate ratio between the amorphous phase and the nanocrystal phase. The nanocrystal structure ensures the high hardness (6.547 ∼ 7.560 GPa) of the ZrNbTiMo film. In addition, the nanocrystals hinder crack propagation, this toughness mechanism effectively improves the toughness of the film. The ZrNbTiMo film prepared at 150 W possesses excellent mechanical properties, hardness of 7.240 GPa and toughness of 0.437 ± 0.040 MPa × m1/2, exhibits better wear resistance (wear rate: 5.223 × 10−7 mm3/N m).Discussion: The wear resistance of ZrNbTiMo film is controlled by both hardness and toughness. The nanocomposite structure makes the ZrNbTiMo films possess a composite fracture which could improve the toughness of the ZrNbTiMo film. The wear-resistant ZrNbTiMo RHEA films with wear rates of the order of 10−6 mm3/N m have been prepared by tuning the sputtering power, this film can be used as a potential candidate for wear-resistant coatings.

Evaluation of photocatalytic activity, water contact angle, and annealing for TiO2 thin films deposited with mixed WOX–SiO2 thin films using radiofrequency sputtering

A mixture of hydrophilic silicon dioxide (SiO2) and visible-light-reactive tungsten oxide (WOX) has the potential to improve the photocatalytic activity of conventional titanium dioxide (TiO2). This study deposits mixed WOX–SiO2 thin films on TiO2 surfaces by controlling the composition of WOX:SiO2 using radiofrequency sputtering to improve photocatalytic activity and hydrophilicity. The photocatalytic activity is evaluated via the degradation of a methylene blue solution, and hydrophilicity is measured using the water contact angle. In addition, the effect of annealing is determined at 400 °C after deposition. The optical bandgap decreases as the composition of WOX increases and subsequently anneals. The XRD measurements show that polycrystalline monoclinic WO3 peaks appear after annealing when the composition of the mixed WOX–SiO2 thin films only consists of WOX. In contrast, monoclinic WO3 (200) appears after adding SiO2. Atomic force microscopy images show that the grain size decreases as the SiO2 content increases. Moreover, the photocatalytic activity of the mixed WOX–SiO2 thin films improves after annealing. In particular, the mixed WOX–SiO2 thin films that are deposited at a sputter power of WOX:SiO2 = 100:50 W demonstrate a remarkable improvement in photocatalytic activity. Furthermore, the water contact angle of the mixed WOX–SiO2 thin films decreases as the SiO2 content increases and after annealing. This proposed approach can be used for high-performance photocatalytic materials and be widely applied for the fabrication of various semiconducting devices.

Polycrystalline WO3−x Thin Films Obtained by Reactive DC Sputtering at Room Temperature

Tungsten oxide thin films have applications in various energy-related devices owing to their versatile semiconductor properties, which depend on the oxygen content and crystalline state. The concentration of electrons increases with intrinsic defects such as oxygen vacancies, which create new absorption bands that give rise to colored films. Disorders in the crystal structure produce additional changes in the electrical and optical characteristics. Here, WO3-x thin films are prepared on unheated glass substrates by reactive DC sputtering from a pure metal target, using the discharge power and the oxygen-to-argon pressure ratio as control parameters. A transition from amorphous to polycrystalline state is obtained by increasing the sputtering power and adjusting the oxygen content. The surface roughness is higher and the bandgap energy is lower for polycrystalline layers than for amorphous ones. Moreover, the electrical conductivity and sub-bandgap absorption increase as the oxygen content decreases.

Magnetron-sputtered Mg-Ga co-doped ZnO transparent conductive thin films: Microstructural and optoelectrical investigation

The Mg–Ga co-doped ZnO (MGZO) transparent conducting thin films (TCTFs) were fabricated via magnetron-sputtering. The dependence of microstructural, morphological and optoelectrical characteristics on sputtering power was investigated. The findings demonstrate that all the TCTFs present a wurtzite hexagonal crystal structure and (002)-preferred orientation. The sputtering power has a significant impact on the properties of the TCTFs. The sample fabricated at 150 W possesses the highest optoelectrical performance and crystalline quality, with the maximum figure of merit, highest average visible transmittance, minimum resistivity, lowest dislocation density and lattice strain of 1.042×104 Ω−1·cm−1, 92.21%, 1.181×10−3 Ω·cm, 1.041×1011 cm−2 and 3.936×10−3, respectively. Moreover, the optical constants (OCs) of the MGZO TCTFs were extracted by the optical spectrum fitting method (OSFM). The dispersion behavior of refractive index (RI) was assessed. The oscillator parameters, optical bandgaps and nonlinear OCs were realized. This study provides a reference basis for the applications of MGZO TCTFs in photoelectronic devices.

Manipulating the optoelectronic characteristic of AZO films by magnetron sputtering power

We investigated the effects of sputtering power on the structure, morphology, electrical and optical properties of AZO films. The results show that all the films show typical hexagonal wurtzite structure with preferred c-axis orientation. When the sputtering power is 120 W, the film has the smallest FHWH value and the largest grain size (24.33 nm), and the AZO thin films obtained the best conductivity, the electrical characteristic parameters are ρ = 3.25 × 10−3 Ω cm， N = 3.512 × 1019 cm−3, μH = 8.642 cm2V−1s−1, respectively. With the increase of sputtering power, the carrier concentration and hall mobility are increasing, which are directly related to the improvement of crystal quality, that is, the higher the crystal quality of the film, the better the conductivity. The average transmittance of all samples is above 80%, and the band gaps increase first and then decreased. This work implies that the application of controllable growth AZO transparent conductive film in photovoltaic devices.