Low Sputtering Power Research Articles

Effect of magnetron sputtering power on the properties of the AlO X monolayer and AlO X /MgF2 bilayer anti-reflection films

The AlO X monolayer anti-reflection (MLAR) films and the AlO X /MgF2 bilayer anti-reflection (BLAR) films were deposited on high-purity glasses with magnetron sputtering. We investigated the influences of sputtering power on the O/Al molar ratio, microstructure, and optical properties of the AlO X MLAR films and AlO X /MgF2 BLAR films. The results showed that a too high or a too low sputtering power was detrimental to the preparation of the high-quality films, which could only be obtained when the sputtering power was 115 W. However, the sputtering power did not affect the crystallinity of the films, all of which were amorphous. When the sputtering power was 115 W, the high-purity AlO X MLAR film exhibited an O/Al molar ratio of 2.27:1, a refractive index of 1.426, and an average transmittance (T avg: average transmittance of the quartz glass deposited the film, hereinafter the same) of 94.03% within 300–1100 nm wavelength range. The T avg of AlO X /MgF2 BLAR film with a power of 115 W was 94.99%, which was 1.92% higher than that of the glass substrate. And it improved the cell’s photoelectric conversion efficiency (PCE) by 3.19%.

Unveiling the orientation growth mechanism and solar-blind response performance of β-Ga2O3 (100) film on SiC substrate with AlN buffer layer

Optimizing the orientation of β-Ga2O3 has emerged as an effective strategy to design high-performance β-Ga2O3 device, but the orientation growth mechanism and approach have not been revealed yet. Herein, by employing AlN buffer layer, the highly preferred orientation of β-Ga2O3 (100) film rather than (-201) film is realized on 4H-SiC substrate at low sputtering power and temperature. Because β-Ga2O3 (100) film exhibits a slower growth speed than (-201) film, the former possesses the higher dangling bond density and the lower nucleation energy, and a large conversion barrier exists between these two orientations. Moreover, the AlN buffer layer can suppress the surface oxidation of the 4H-SiC substrate and eliminate the strain of β-Ga2O3 (100) film, which further reduces the nucleation energy and enlarges the conversion barrier. Meanwhile, the AlN buffer layer can increase the oxygen vacancy formation energy and decrease the oxygen vacancy concentration of β-Ga2O3 (100) film. Consequently, the solar-blind photodetector based on the oriented film exhibits the outstanding detectivity of 1.22 × 1012 Jones and photo-to-dark current ratio of 1.11 × 105, which are the highest among the reported β-Ga2O3 solar-blind photodetector on the SiC substrate. Our results offer in-depth insights into the preferred orientation growth mechanism, and provide an effective way to design high-quality β-Ga2O3 (100) orientation film and high-performance solar-blind photodetector.

An Investigation of the Structural and Surface Topography of Aluminum Nitride Thin Films Deposited at Low Sputtering Power for Piezoelectric Applications

An Investigation of the Structural and Surface Topography of Aluminum Nitride Thin Films Deposited at Low Sputtering Power for Piezoelectric Applications

Preparation and properties of a super-hydrophobic, electromagnetic interference shielding titanium nitride film

A super-hydrophobic, electromagnetic shielding titanium nitride (TiN) film was prepared using reactive magnetron sputtering by adjusting the sputtering power (30, 90, 180 and 250 W). The results showed that preferred orientation of the film had an obvious change with increasing sputtering power. At 30 W, too low sputtering power was not conducive to the crystallization of the film. At 90 W, TiN film grew toward [200] preferred orientation with a flat and compact surface, while the preferred orientation was [111] at 180 and 250 W with an uneven surface. Higher sputtering power could construct a low energy and high roughness surface which was helpful to improve the hydrophobic property. The water contact angle of the as-prepared TiN film at 250 W was 151.3°, indicating the achievement of super-hydrophobic property. Due to the decrease of electrical resistivity, the increase of film thickness and the special microstructure of pyramidal nanoparticles, the electromagnetic shielding effectiveness of TiN film at sputtering power of 250 W was about 40 dB, meaning that TiN film had good expect to be a super-hydrophobic, electromagnetic shielding material in the industrial field.

Optimization of Growth Parameters of the RF-Sputtered CuInGaSe2 Thin Films for Photovoltaic Applications

CuInGaSe2 (CIGS) thin films were deposited by RF sputtering using a single quaternary target. The effects of various sputtering parameters, such as substrate temperature, sputtering power, and gas flow rate, were studied systematically. The structural, morphological, compositional, and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), and UV–vis-NIR spectroscopy. The samples exhibited the chalcopyrite type tetragonal structure of CIGS, as confirmed by the XRD analysis. Raman spectroscopy represents the presence of Cu poor ordered vacancy compound (OVC) phase in all the present samples. The growth of the sample at a higher substrate temperature resulted in a higher crystalline nature with a suppressed OVC phase and energy bandgap of 1.18 eV. The deposition of CIGS at 160 W sputtering power favors growth towards (112) Bragg crystal plane, suppressing the (220)/(204) plane of CIGS, shows change in preferred orientation with a lower sputtering power at 80 and 120 W. The sample grown at a gas flow rate of 60 standard cubic centimeters per minute (SCCM) exhibited compact grain growth with marginally improved crystallinity. The sample grown at 160 W, 300 °C, and 60 SCCM showed better crystalline and morphological properties, and it can be used as an absorber layer for highly efficient CIGS thin-film solar cells.

Microstructure and adsorption characteristics of Zr–Co–RE getter films deposited using krypton as sputtering gas

The vacuum level in micro-electro-mechanical system devices needs to be achieved and maintained using non-evaporable getter film technology. Zr–Co–RE getter films are deposited by direct current (DC) magnetron sputtering using krypton (Kr) as the sputtering gas. The influence of sputtering gas pressure and DC sputtering power on the microstructure and adsorption characteristics of films is investigated. Zr–Co–RE films deposited at different gas pressures all grow in a columnar shape. Films grown at low Kr pressures are relatively dense and have a structure with fewer cracks, whereas high Kr pressures result in a uniform cluster and columnar structure with more gaps and micro-cracks. In addition, it is revealed that DC sputtering power has great influence on the film structure and adsorption performance. The films deposited at low sputtering power contain more micro-cracks, which are distributed uniformly. At high sputtering power, the cluster structure is not obvious. Consequently, high Kr pressures and low sputtering power are beneficial to improve the adsorption performance. Hydrogen adsorption tests are carried out using a special vacuum system, keeping the pressure constant. The highest initial adsorption speed is 89 (ml/s)/cm2, obtained at 4.0 Pa Kr pressure and 300 W sputtering power. Meanwhile, the Zr–Co–RE films deposited under these conditions have excellent adsorption stability.

Depth distribution analysis of alloying and impurity elements in Ni-Ti alloy thin films using secondary ion mass spectrometer

Ni-rich Ni-Ti thin films of various compositions and thickness (69 nm - 141 nm) were deposited on Si (111) substrate by magnetron sputtering system using equiatomic NiTi alloy sputtering target. X-ray reflectivity analysis of the thin films deposited at room temperature showed the presence of a layered structure as: NiO/Ni-Ti/NiO/SiO2 on Si substrate. Secondary ion mass spectrometry (SIMS) was used to determine the qualitative (intensity) depth distribution of elements Ni, Ti, O and Si in the films using MCs+ approach. Relative sensitivity factor values were utilized to convert the qualitative depth profiles to concentration depth profiles. Surface and depth distribution of alloying elements in the deposited films were investigated. It was observed that the films deposited at high sputtering power and working pressure resulted in more non-uniform depth distribution of alloying elements compared to films deposited at low sputtering power and working pressure. SIMS depth profile data showed the presence of high oxygen contaminations at the surface and at the interface of the films. The Ti concentration in the deposited films depends upon the background oxygen contamination present in the deposition chamber during sputtering process. The concentration of Ni in the films deposited under similar working pressure increases with increase in the sputtering power. However, with increase in working pressure during deposition process results in decrease in the concentration of both Ni and Ti in the deposited films. In order to study the effect of insitu substrate heating on the distribution of alloying and impurity elements, one of the film was deposited on heated Si substrate. The film deposited on heated substrate represents the layer structure as NiTiO3 on Si substrate. The concentration of oxygen in the film deposited on heated substrate is comparatively higher than those deposited at room temperature.

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.

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.

Magnetic Properties Regulation of FeGa and FeGaNi Films with Oblique Magnetron Sputtering

Magnetic FeGa and FeGaNi films with an in-plane anisotropy were deposited by employing oblique magnetron sputtering. With the increase in oblique angle, the crystallite size of FeGa decreases, which indicates that oblique sputtering can refine the crystallite size. The remanence ratio of FeGa films increases from 0.5 to 0.92 for an easy axis, and the coercivity increases with the decrease in the crystallite size. The calculated static anisotropic field shows that the in-plane magnetic anisotropy can be induced by oblique sputtering and the strength increases with the oblique sputtering angle. After doping Ni by co-sputtering, FeGaNi films exhibit a stable remanence ratio at 0.8, low coercivity and good anisotropy. With the low sputtering power of the Ni target, there is a competitive relationship between the effect of crystallite size and Ni doping which causes the coercivity of FeGaNi films to first increase and then decrease with the increase in the oblique angle. The FeGaNi film also shows high anisotropy in a small oblique angle. The variation of coercivity and anisotropy of FeGaNi films can be explained by the crystalline size effect and increase in Ni content. For the increasing intensity of collisions between FeGa and Ni atoms in the co-sputtering, the in-plane magnetic anisotropy increases first and then decreases. As a result, the magnetic properties of FeGa films were examined to tailor their magnetic softness and magnetic anisotropy by controlling the oblique sputtering angle and Ni doping.

Study on the resistivity and infrared emissivity of TiNx films at different sputtering power

TiNx films with low infrared emissivity were prepared using DC reactive magnetron sputtering technique. The influence of sputtering power (50, 80, 100, and 200 W) on the morphology, structure, adhesion force, resistivity and infrared emissivity was investigated systematically. The thickness of the prepared TiNx films was in the range of 381–987 nm. The films grew with preferred orientation of (200) plane at lower sputtering power, while the preferred orientation was (220) plane at higher sputtering power. The N/Ti stoichiometry ratio increased from 0.67 to 0.96 with the increase of sputtering power, and the deposited TiNx thin films were off stoichiometry. Due to more formation of bonds of Ti–N in TiNx crystal, the adhesion force increased with increasing of sputtering power. The resistivity and infrared emissivity of TiNx films first deceased, and then increased with the increase of sputtering power. Defects in TiNx films prepared at 50 W led to high resistivity and infrared emissivity. The lattice distortion caused by Ti atoms was considered to play an important role in the increase of the resistivity of TiNx films at 200 W. The decrease of carrier density caused by decreased nitrogen vacancies should be the reason for the increase of the infrared emissivity of TiNx films at 80–200 W.

The Corrosion Resistance of Al Film on AZ31 Magnesium Alloys by Magnetron Sputtering

Nano Al films were prepared on AZ31 magnesium alloy samples by DC magnetron sputtering. The effects of sputtering power on the microstructure and corrosion resistance of the Al film were investigated. The results show that the surface of aluminum film is dense and polycrystalline state, and it is oriented along the Al (111) crystal plane. The grain size of Al film first increases and then decreases with the increase of sputtering power. When the sputtering power exceeds 100 W, there is no insignificant effect on the orientation of the Al crystals and the corrosion current density of the samples with Al film are reduced by two orders of magnitude. The corrosion resistance of the magnesium alloy samples with the Al film magnetron sputtered varies with the sputtering power. Compared with low sputtering power, the Al film sputtered by high power has the most excellent corrosion resistance, but too high sputtering power will lead to micro cracks on the Al film, which will adversely affect the corrosion resistance.

Magnetron sputtering technique for analyzing the influence of RF sputtering power on microstructural surface morphology of aluminum thin films deposited on SiO2/Si substrates

In this research, aluminum (Al) thin films were deposited on SiO2/Si substrates using RF magnetron sputtering technique for analyzing the influence of RF sputtering power on microstructural surface morphologies. Different sputtering RF powers (100–400 W) were employed to form Al thin films. The characteristics of deposited Al thin films are investigated using X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier-transforms infrared (FTIR) spectroscopy. The X-ray diffraction (XRD) results demonstrate that the deposited films in low sputtering power have amorphous nature. By increasing the sputtering power, crystallization is observed. AFM analysis results show that the RF power of 300 W is the optimum sputtering power to grow the smoothest Al thin films. FTIR results show that the varying RF power affect the chemical structure of the deposited films. The SEM results show that by increasing the sputtering power leads to the formation of isolated texture on the surface of substrate. In conclusion, RF power has a significant impact on the properties of deposited films, particularly crystallization and shape.

Structural and mechanical properties of amorphous Si–C-based thin films deposited by pulsed magnetron sputtering under different sputtering powers

Amorphous Si–C-based (a-SiC) thin films as protective coating have been attracting more and more attentions. But there are contradictory reports in the literature about the effect of sputtering power on the structural and mechanical properties of a-SiC films. Here, the influence of sputtering power on structural and mechanical properties of a-SiC thin films deposited by pulsed magnetron sputtering have been investigated. The results show that as-prepared films have a columnar structure and cauliflower-like pattern at lower sputtering power (100 W). Increasing the sputtering power from 100 W to 180 W, the columnar feature disappears and the thin films become denser. Meanwhile, the density of Si–C bond increases and the sp3/sp2 radio decreases. The hardness (H) and elastic modulus (E) of the a-SiC thin films increase when the sputtering power increases from 100 to 120 W and then their almost keep constant when the sputtering power increases from 120 to 140 W. Further increases in sputtering power, the H and E increase again. The maximum H and E are about 20.2 GPa and 223.1 GPa at 180 W, respectively. Reason for excellent mechanical property is proposed in combination with the theory analysis and experiment results.

Assembly and Electroluminescence of Sheet-Like Zinc Oxide/Silicon Light-Emitting Diode by Radio Frequency Magnetron Sputtering Technique.

Sheet-like Zinc Oxide/Silicon ([ZnO]/[Si]) light emitting diode (LED) has been fabricated through depositing nanoscale ZnO on the p-type single crystal silicon by using a radio frequency (RF) magnetron sputtering method. The (100), (002) and (101) diffraction peaks can be observed. With the increasing sputtering time, however, the intensity of (100) and (101) diffraction peaks has gradually decreased and the intensity of (002) diffraction peak has gradually enhanced. Through low the sputtering power, the obtained ZnO shows better (002)-orientation growth. Electroluminescence (EL) from [ZnO]/[Si] LED have been decomposed into three emission bands, i.e., UV, green and orange emissions, which origin from the band gap, zinc interstitial or vacancies oxygen and shallow level, respectively. At the low sputtering power, orange emission is disappeared. It is indicated that the structures and EL properties are sensitive to the fabrication conditions. It is important to optimize and tune the fabrication condition for purposeful application in the future works.

Tailored Hydrogen-Free Carbon Films by Tuning the sp2/sp3 Configuration

Carbon configuration is a critical factor in determining the electrical, tribological, and mechanical properties of carbon films. In this work, we synthesized carbon films on a silicate glass by sputtering a graphite target in an Ar atmosphere while varying the DC sputtering power. Using Raman spectroscopy and photoemission analysis, we found that the carbon films produced at low sputtering power consisted mainly of sp3 bonds, while sp2 carbon ordering became dominant as the sputtering power increased. The sp2/sp3 ratio of the carbon film controlled by the sputtering power is associated with two competing carbon deposition mechanisms: (1) collision between the incoming carbon ions and surface carbon atoms at low power (sub-plantation model) and (2) sp3-to-sp2 rehybridization caused by excessive kinetic energy of the incoming carbon ions at high power (thermal relaxation). As the sputtering power increased, the friction, adhesion, and energy dissipation decreased, despite negligible topographical variations, while the conductivity rapidly increased. We fabricated a triboelectric nanogenerator with high durability by utilizing the low friction properties of the sputtered carbon films. Our results show a straightforward and effective way to control the properties of carbon films, which can be used as promising coating films for frictionless protection.

Surface plasmonic resonance tunable nanocomposite thin films applicable to color filters, heat mirrors, semi-transparent electrodes, and electromagnetic-shields.

This study proposes a plasmonic resonance-tunable nanocomposite thin film, which applies to a color filter, heat mirror, semi-transparent color electrode, and electromagnetic shield, given that the size and structure of nanoclusters can be controlled by a sputtering power density. The structural and functional properties of silver/plasma-polymer-fluorocarbon (Ag/PPFC) nanocomposite thin films, which were sputtered by ternary composite targets, were investigated with various compositions and sputtering power densities. The growth of Ag nanoclusters of the thin film was suppressed as the sputtering power density increased due to the rich functional group of -CFx- fluorine. As a result, a continuous color change from blue to yellow could be expressed on films given the precise control of the surface plasmonic resonance phenomenon. Grazing-incidence small-angle scattering (GISAXS) analysis indicated that the sputtering power density had a significant effect on the size, distribution, and orientation of the Ag nanoclusters in the thin film. For low sputtering power densities, Ag nanoclusters were forming aggregations along the out-of-plane direction, but as the sputtering power density increased, the nanoclusters showed random distribution instead of large aggregates. We also demonstrated applications of Ag/PPFC nanocomposite thin films to a color filter, heat mirror, semi-transparent electrode, and electromagnetic shield. In addition, the fabrication of a large-area film (400 × 700 mm2) showed that the approach applies highly to industries.

Tunable p- and n-type Nb:TiO2 and performance optimizing of self-powered Nb:TiO2/CdS photodetectors

For the first time, Niobium-doped titanium dioxide (Nb:TiO2, NTO) and cadmium sulfide (CdS) are selected for building self-powered photodetectors for optimizing the performance. The p- or n-type NTO and the band structures of the heterojunctions can be controlled by doping Nb and tuning the sputtering power. A low sputtering power tends to produce pure anatase crystals and a high power induces an additional rutile phase aligned in the (200) orientation. NTO films deposited at a sputtering power of 120 W show p-type behavior attributed to the compensation of oxygen vacancies. NTO films deposited at 180 W contain mixed anatase and rutile phases with lattice imperfections and show n-type semiconductor properties after annealing. By measuring the energy band structure of the n-n-type anatase-TiO2/CdS, p-n-type anatase-NTO/CdS, and n-n-type mix-NTO/CdS heterojunctions, we identify the interface carrier motion characteristics and tune the energy band structure to optimize the performance of the photodetectors. Without any external power supply, the responsivities reach at least 0.125A/W in the mix-NTO/CdS (light source: 550 nm) and the response speed is lower than 10 ms, which can be used for building a self-powered photodetector.

Impact of bilayer structures on the surface passivation quality of high‐rate‐sputtered hydrogenated amorphous silicon for silicon heterojunction solar cells

AbstractCrystalline silicon surface passivation effect of intrinsic hydrogenated amorphous silicon (i‐a‐Si:H) films deposited by radio‐frequency facing target sputtering (RF‐FTS) using a two‐step deposition technique was investigated. In the two‐step deposition technique, an i‐a‐Si:H layer was deposited at a high sputtering power condition after the deposition of i‐a‐Si:H at a low sputtering power condition. The two‐step deposition technique drastically improved the passivation quality of i‐a‐Si:H compared with a conventional single‐step deposition technique. Only 0.5‐nm‐thick i‐a‐Si:H deposited at a low sputtering power suppresses the initial sputtering damage to the crystalline silicon surface. A high average deposition rate of 14.1 nm/min was also achieved. A non‐textured silicon heterojunction solar cell using an i‐a‐Si:H passivation layer deposited by the two‐step method shows a conversion efficiency of 17.4% (Voc = 0.679 V, Jsc = 35.0 mA/cm2, FF = 0.732).

Growth and infrared switching properties of deposited VO2 films at various sputtering power with a VO2 target by RF magnetron sputtering

In this work, structural and morphological properties as well as phase transition temperature and hysteresis width of VO2 thin films grown with a VO2 target by RF magnetron sputtering were studied under the influence of relatively low sputtering power of 80 – 140 W. It was observed that as sputtering power increased, the crystallinity of the films improved with the presence of obvious diffraction peaks of VO2, and a slight increase in the average crystallite and grain sizes of the films. The deposited films revealed a slight change in infrared transmittance during heating and cooling cycles. Films deposited at sputtering power of 140 W exhibited the lowest Tt of 60.5 °C with a hysteresis width of 41.0 °C.