Direct Current Magnetron Sputtering Method Research Articles

Structure Evolution and Formation Mechanism of Wrinkled Fe Films on Liquid Surfaces

A characteristic wrinkled Fe film system has been prepared on silicone oil surfaces by a direct current magnetron sputtering method. The experiment shows that the Fe film is under a large compressive stress induced by the thermal contraction during deposition, which is relieved by the formation of wrinkling patterns. It is found that the wrinkling patterns, such as straight strips and herringbones, are formed in networked domains. The straight strips are perpendicular to the domain edges and the herringbones are located in the center of the domains. The morphologies of the wrinkled patterns are characterized by the optical microscopy and atomic force microscopy. It is found that the average length d of the domains remains nearly unchanged and the wavelength λ of the wrinkling patterns increases linearly with the film thickness h, which obeys an equation λ = 14h + 1440. The amplitude z of the herringbones increases firstly with the film thickness h for h ≤ 450 nm and decreases quickly for h > 450 nm. The characteristic, structure evolution and formation mechanisms of the wrinkled patterns have been described and discussed in detail.

Wafer Bonding of SiC-AlN at Room Temperature for All-SiC Capacitive Pressure Sensor.

Wafer bonding of a silicon carbide (SiC) diaphragm to a patterned SiC substrate coated with aluminum nitride (AlN) film as an insulating layer is a promising choice to fabricate an all-SiC capacitive pressure sensor. To demonstrate the bonding feasibility, a crystalline AlN film with a root-mean-square (RMS) surface roughness less than ~0.70 nm was deposited on a SiC wafer by a pulsed direct current magnetron sputtering method. Room temperature wafer bonding of SiC-AlN by two surface activated bonding (SAB) methods (standard SAB and modified SAB with Si nano-layer sputtering deposition) was studied. Standard SAB failed in the bonding, while the modified SAB achieved the bonding with a bonding energy of ~1.6 J/m2. Both the microstructure and composition of the interface were investigated to understand the bonding mechanisms. Additionally, the surface analyses were employed to confirm the interface investigation. Clear oxidation of the AlN film was found, which is assumed to be the failure reason of direct bonding by standard SAB.

Effect of sputtered Cu2ZnSnS4 film thickness on dye sensitized solar cell counter electrode performance

Cu2ZnSnS4 (CZTS) films were deposited on the fluorine doped tin oxide substrates using a two-step process. First step, the Cu/Zn/Sn precursors were coated on conductive glass using a direct-current magnetron sputtering method. Second step, Cu/Zn/Sn films were annealed at 600 °C for 1 h under a sulfur atmosphere. X-ray diffraction and Raman spectroscopy indicated kesterite Cu2ZnSnS4 formation. CZTS films were used as the counter electrodes (CEs) of dye-sensitized solar cells. The solar cell efficiency and the short circuit current density increased with increasing CZTS film thickness. The maximum solar cell efficiency based on CZTS CEs reached 6.27% at film thickness of 3.7 ± 0.8 μm, compared to a Pt based dye-sensitized solar cell of 7.52%.

Influences of the Ag and the ITO Thicknesses on the Optical and the Electrical Properties of ITO/Ag/ITO Multilayer Films

We studied the electrical and the optical properties of indium tin oxide (ITO) (t1)/Ag (t0)/ITO (t2) (IAI) multilayer thin films based on the variations in the thicknesses of the Ag and the top and bottom ITO layers. The IAI multilayer thin films were deposited on soda lime glass (SLG) substrates by using radio-frequency and direct-current magnetron sputtering methods at room temperature. The deposited IAI multilayer thin films were analyzed using X-ray diffraction, UV-Visible spectroscopy, and Hall measurements. The optical transmittance at a wavelength of 550 nm was 91.7% for the IAI thin films having 9 nm-thick Ag and 50 nm-thick top and bottom ITO layers. The sheet resistance and mobility decreased with the increasing Ag thickness t0 from 4.5 nm to 18 nm while they varied little with the thicknesses (t1, t2) of the top and the bottom ITO layers. The best optical and electrical performance of the IAI layer was obtained for the sample with 50 nm-thick top and bottom ITO layers (t1 = t2 = 50 nm) and the optimum Ag layer (t0 = 9 nm).

MICROSTRUCTURE AND PROPERTIES OF COATING OF AlFeCrNiMo HIGH-ENTROPY ALLOY

High-entropy alloys (HEAs) have recently received significant attention in the materials science community. Some of these alloys can display a good combination of mechanical properties. The perfect dense and smooth coatings of AlFeCrNiMo HEA have been deposited by direct current magnetron sputtering method. The coatings possess single BCC crystal structure. The thickness of the coatings increases with increasing deposited time and plasma power. The coatings display excellent high hardness and Young’s modulus. The corrosion resistance of all coatings in acidic and salt media is better than that of 201 stainless steel. It is expected that the HEA coatings have very broad application prospects.

Studying the influence of deposition temperature and nitrogen contents on the structural, optical, and electrical properties of N-doped SnO2 films prepared by direct current magnetron sputtering

This report focuses on studying and investigating in detail the structural, electrical, and optical properties of p-type N-doped SnO2 (NTO) versus the deposition temperature and nitrogen content. P-type transparent conductive NTO films were deposited on quartz glass substrates using a direct current (DC) magnetron sputtering method. The substitution of oxygen by nitrogen in the SnO2 host lattice was verified using measurements such as X-ray photoelectron spectroscopy. The position of the N3− defect state in the band gap was determined using photoluminescence and ultra-violet-visible spectroscopy measurements. The data for the (110) to (101) rutile lattice planes changed, and the rutile (plane (101)) to cubic (plane (111)) SnO2 phase transition indicated the substitution of oxygen by nitrogen in the SnO2 host lattice. The best p-type conductive properties achieved were 8 × 10−2 Ω cm, 1.36 × 1019 cm−3, and 6.75 cm2 V−1 s−1 for the resistivity, hole concentration, and hole mobility, respectively, for film deposited at the optimum substrate temperature of 300 °C in a gas mixture of Ar and 50% N2.

Effect of SiNx interlayer thickness on adhesion and friction properties of diamond-like carbon films

A suitable interlayer thickness is critical to reduce film mismatch and roughness. In this text, diamond-like carbon (DLC) films with different SiNx interlayer thicknesses were successfully synthesized on Si (100) substrates by radio frequency (RF) and direct current (DC) magnetron sputtering method. The effect of SiNx interlayer thickness on surface morphology, adhesion, tribological and mechanical properties of DLC films was investigated. The results show that, due to the use of SiNx interlayer in the DLC films, the adhesion is significantly enhanced, the surface roughness is increased, and the sp3 content and modulus are lowered. When the SiNx interlayer is introduced, the internal stress and the roughness decrease first decrease and then increase. The reason may be related to the accumulation of nitrogen vacancy centers (NVC). A sample of about 10 nm SiNx interlayer was found to have the best combination of tribology, mechanical properties, and surface roughness.

Titanium dioxide and suboxide thin films grown with controlled discharge voltage in reactive direct-current sputtering

We have grown titanium dioxide and suboxide thin films using reactive direct-current magnetron sputtering methods. By monitoring the discharge voltage and plasma optical emission spectra at a constant current mode during the growth, we identified the oxidized conditions of metal target as well as the energy of plasma species, which characteristics were directly revealed in the structural and chemical properties of as-grown titanium oxide thin films. The films with a higher discharge voltage and a higher population of TiO* plasma turned out to have a dioxide configuration while ones with a lower voltage and a higher Ti* plasma are of multiple phases with suboxide counterparts.

A Novel Type Room Temperature Surface Photovoltage Gas Sensor Device.

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. It is based on the Kelvin probe approach. Porous ZnO nanostructured thin films deposited by the direct current (DC) reactive magnetron sputtering method are used as the active gas sensing electrode material. Crucially, the obtained gas sensing material exhibited a nanocoral surface morphology and surface Zn to O non-stoichiometry with respect to its bulk mass. Among other responses, the demonstrated SPV gas sensor device exhibits a high response to an NO2 concentration as low as 1 ppm, with a signal to noise ratio of about 50 and a fast response time of several seconds under room temperature conditions.

Preparation and performance of low-emissivity Al-doped ZnO films for energy-saving glass

Low-emissivity Al-doped ZnO films were deposited on the surface of glass by direct current magnetron sputtering method. The infrared emissivity of sample was focused on. The structural characteristics were investigated by the X-ray diffractometry and scanning electron microscopy, while the properties were measured by a four-point probe, an infrared emissivity measurement instrument and an UV–Vis spectrophotometer. The results show that the infrared emissivity of the AZO film is affected by substrate temperature, working pressure and sputtering power. The film deposited at 200 °C, 1.0 Pa and 80 W possesses the lowest emissivity, 0.41. There is a very strong correlation between emissivity and resistivity. When the resistivity is low, the infrared emissivity increases with the increase of resistivity, following the Hagen-Rubens relationship. When the resistivity is high, the correlation between them decreases.

Characterization of the microstructure and the optical and electrical properties of the direct-current magnetron sputtered CuO films at different substrate temperatures

Single-phased monoclinic CuO films with direct energy gap were deposited on the clean glass substrates by direct-current magnetron sputtering method. Effect of substrate temperature was in particular studied on the microstructure, and the optical and electrical properties of the films. With increase in substrate temperature, the crystallization of the polycrystalline CuO films is enhanced and thus the CuO film at substrate temperature of 600 °C has a clear <111> preferred orientation. Substrate temperature has different effect on the stress along the crystal axis a, b, and c, indicating an anisotropic growth along different crystal axis. The absorption edge of the films in the vicinity of 1.88 eV first moves towards short wavelength direction and then towards long wavelength direction with substrate temperature, which can be explained by the quantum size effect of the crystallites. The conduction transition of the films from p to n type takes places at substrate temperature of 500 °C. The p-type conduction is attributed to the copper vacancies and interstice oxygen, while n-type conduction is to the oxygen vacancies and interstice copper. The CuO film deposited at high substrate temperature has a larger carrier concentration and a lower electrical resistivity.

Reliability and characteristics of magnetron sputter deposited tantalum nitride for thin film resistors

Tantalum nitride (TaN) films were deposited onto SiO2/Si and multilayer ceramic (MLC) substrates with a reactive direct current magnetron sputtering method. After they were kept at different N2 partial pressures and substrate temperatures, these were characterized for their electrical, structural, and mechanical properties for use as thin film resistors (TFRs). Results of X-ray diffraction analysis, observation of microstructure, sheet resistance measurement, and accelerated degradation tests highly indicated that TaN films with high crystalline phases, good surface roughness, stable deposition rates, appropriate sheet resistances, and high reliabilities could be obtained if N2 partial pressure was maintained at around 20%. Adhesive strengths of TaN films grown on MLC substrates were increased with increasing substrate temperature up to 300 °C. A low resistance change was confirmed by temperature coefficient of resistance variation as a function of temperature, implying high reliability and durability. Results of this study suggest that TFRs described in this study are suitable for embedded passive resistors with practical applications, including controlled resistances for fabricated TaN based TFRs with different widths.

Switching properties of switchable mirrors using palladium-ruthenium catalytic layers

In preparing switchable mirrors, palladium (Pd) was used as a catalyst for hydrogenation and dehydrogenation, and to prevent oxidation of the switchable layer. To reduce the cost, Pd was alloyed with ruthenium (Ru) and used as a catalytic layer, since the price of Ru is approximately one-tenth that of Pd. Switchable mirrors of magnesium-yttrium (Mg-Y) alloy thin films coated with a Pd-Ru layer were prepared by direct-current magnetron sputtering method. Their optical switching properties between reflective and transparent states were studied using gasochromic method. The mirrors coated with Pd1-αRuα of up to α ≈ 0.6 showed nearly the same switching time from reflective to transparent state as those coated with pure Pd, while the mirrors coated with Pd1-αRuα of 0.2 ≤ α ≤ 0.4 showed shorter switching times from transparent to reflective state than those coated with pure Pd. Furthermore, the alloy-coated mirrors with shorter switching times had approximately 2–3 times higher switching durability than those coated with pure Pd. These shorter time and higher durability may be because Pd-Ru alloy prevents oxidation of the underlying layers more effectively than pure Pd. Thus, Pd-Ru alloy is one of the most promising catalysts for switchable mirrors.

Crystal structure and optical properties of silver-doped copper nitride films (Cu3N:Ag) prepared by magnetron sputtering

Silver-doped copper nitride (Cu3N:Ag) films were prepared by using radio frequency and a direct current magnetron sputtering method. The effects of silver doping on the crystal structure, surface morphology, and optical properties of the films were investigated. Results demonstrated that Ag doping influences the preferred growth orientation of the films. With the increased Ag content, the films grow from the (1 0 0) crystal face to the (1 1 1) crystal face. Ag doping changes the lattice constant, grain size, and optical band gap of Cu3N:Ag films. Cu3N:Ag films achieve the most remarkable crystallinity at 0.23 at% of Ag with lattice constant and optical band gap of 0.381 88 nm and 1.30 eV, respectively. Moreover, the doped Ag atoms fill the hollows in the Cu3N lattice and consequently reach the high-energy defect level. These atoms also generate impurity compound centers at high-energy level, shorten the non-equilibrium carrier lifetime of the films, and weaken the electronic transportation of the films.

Fabrication and characterization of interdigital capacitors thin film by DC magnetron sputtering for measuring the permittivity of crude oil

The Interdigital Capacitors (IDCs) are integrated circuits within metal fingers electrode for measurement of specific properties. A new model has been carried out for fabrication and characterization of silver and copper thin film electrode of IDCs for the measurement of crude oil permittivity. Thin film electrode was fabricated by Direct Current (DC) Magnetron Sputtering method using silver and copper target on Flame Resistant (FR)-4 Printed Circuit Board (PCB). The electrode configuration was composed in seven designs.The experimental results show that, IDCs thin film has a great potential to determine the permittivity of crude oil.

Synthesis and photoluminescence properties of thermal oxidized CuO nanorods from sputtered Cu films

The unique physical and chemical properties of CuO nanostructures make them as the key materials for the application of nano-optoelectronic devices, gas sensors and photodetectors. Although thermal oxidation is a simple, high efficient and low-cost preparation method, the cracking problem caused by heating still limits its wide application in nano-devices. Therefore, it is still necessary to develop the preparation techniques, which can grow CuO nanostructures directly on various substrates, especially the widely-used Si wafer. Photoluminescence (PL) is a nondestructive technique to explore the optical properties and investigate the electronic transitions in semiconductors, which is important to develop the photo-electronic devices. This research is important to promote the practical applications of CuO nanostructures in functional devices. In this work, Cu films with different morphologies are firstly achieved from two different direct current (DC) and radio frequency (RF) magnetron sputtering method. Then, the electric field assisted thermal oxidation method is introduced to grow CuO nanostructures from Cu films. Two different thermal oxidation processes are used to explore the effect of the electric field directions. Besides, Cu foils are also oxidized in the same condition for comparison. The morphologies and crystal structures of Cu films and CuO nanostructures synthesized in different technologies are characterized via scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM). Finally, PL spectra of CuO nanorods are also measured at room temperature by Horiba FluoroMax-4 fluorescence spectrometer. The results show that a columnar Cu film with the thickness of 1.25 μm is obtained from DC magnetron sputtering, whose preferred orientation is (111) plane. CuO nanowires are found on the Cu foils oxidized under two heating conditions. However, for the columnar Cu films, CuO nanorods are only obtained under an upward electric field, which is same to the growth direction of the nanorods. A layer structure of CuO nanorods/CuO layer/Si substrate is formed after thermal oxidation, and it is found exfoliated from the Si substrate. So, a thin Cr buffer layer of about 100 nm is deposited before Cu layer to enhance the film-substrate bonding force. It turns out that the Cr layer can solve the cracking problem caused by thermal stress. The TEM results show that the CuO nanorod is a monocrystal monoclinic phase with diameter of about 40 nm. Besides, the lattice spacings of the CuO nanorod are bigger than the standard spacings. As for the RF magnetron sputtering, although fine grain Cu film of about 0.5 μm is successfully obtained on Si substrate, no one-dimensional nanostructured oxides are found after two thermal oxidation conditions. The most close-packed plane of FCC Cu structure is (111) plane, whose surface energy is minimum. Therefore, it is easier for the film deposited by DC magnetron sputtering to grow along the (111) plane due to the smaller ion energy compared with the RF magnetron sputtering. Furthermore, the DC-deposited columnar Cu film are easier to form CuO nanorods than the RF-deposited fine grain Cu film, because the cracks among columnar crystals provide a high diffusion rate channel for the diffusion of ions. No Cu2O phase is found in this work due to the limited supply of Cu compared with the Cu foils. The CuO nanorods excited with ultraviolet light show wide dark violet to bright blue luminescence band in the range from 390 to 470 nm at room temperature. This study is beneficial to further understand the growth mechanism and optical properties of CuO nanorods and assemble novel functional devices based on Si-CuO nano-arrays.

Application and parameter identification of cohesive zone elements for intergranular fracture in thin layer

AbstractCoating layers are usually applied on different manufacturing tools to improve their wear resistance and surface properties of the final parts. In this work, fracture and damage behavior of hard coatings such as (Cr,Al)N is studied. The coatings are produced by means of direct current magnetron sputtering (dcMS) and high power pulsed magnetron sputtering (HPPMS) method. The fracture properties of the coating are measured by investigating the force‐displacement curve obtained from a bending test [1]. The cohesive zone element parameters are then fitted to the experimental results to simulate the same behavior. The intergranular fracture within the coating system can then be modeled by employing the cohesive zone (CZ) regions at grain boundaries [2]. (© 2017 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Excellent photochromic properties of an oxygen-containing yttrium hydride coated with tungsten oxide (YHx:O/WO3)

Oxygen-containing yttrium hydride films (YHx:O) show interesting photochromic properties under ultraviolet irradiation. In this paper, oxygen-containing yttrium hydride films covered with tungsten oxide were prepared by a direct current magnetron sputtering method. This composite material showed reversible photochromic properties. Furthermore, its coloration speed was faster than that of a single layer of yttrium hydride, and its switching modulation was broader. The photochromic mechanism of the YHx:O/WO3 thin films was investigated by X-ray diffraction, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy analysis. Oxygen and hydrogen played a key role in the photochromic process of the YHx:O/WO3 composite films.

Soft Magnetic Properties of HfxCo100−x Thin Films

HfxCo100−x thin films (in the atomic weight range of x = 30–36) were growth on Si (100) substrates by direct current (DC) magnetron sputtering method. Thin films produced with atomic compositions in this context depicted the amorphous structure. The films revealed soft magnetic properties and thus exhibited very low hysteresis along the hard-axis direction. Magnetic measurements indicated that Hf35Co65 thin film has the maximum saturation magnetization (1491 emu cm−3) at 300 K. Additionally, magnetization measurements show an increase in saturation magnetization value from 981 to 1491 emu cm−3 when the value of x varies between 30 and 35. The influence of varying sputtering pressure and film composition on soft magnetic properties are investigated and discussed in the present paper.

Study on the hydrogen doped indium oxide for silicon heterojunction solar cell application

In this work, we presented a comparative investigation on the physical properties of hydrogen doped indium oxide (In2O3:H) films by the direct current magnetron sputtering method. Comparing with the traditional ITO films, the In2O3:H films have lower carrier density, higher Hall mobility and wider transmittance range for optimized O2 and H2 flow rates. At a critical H2 flow rate of 2.5 sccm, an electron mobility of ∼100 cm2/V·s was achieved after the air-annealed treatment. Note that this is the best value for In2O3:H films with H2 gas as the doping source for low temperature preparation as far as we know. In our case, the adding of H2 flow rate during the sputtering process increased the carrier concentration of In2O3:H films. Unexpectedly, higher Hall mobility was also achieved at the same time. This could be attributed to the mechanism that hydrogen impurities induced some shallow donors in In2O3:H, which had low scattering effect on the carrier transporting. Besides, a high transmittance was obtained at the low resistivity condition, which makes the In2O3:H films ideal candidate for solar cell application. Further, the resulting In2O3:H films were employed as the front anti-reflecting contact layer in large scale amorphous/crystalline silicon heterojunction solar cells, and remarkable device performances were achieved with a conversion efficiency of 21.13%, open-circuit voltage of 0.7296 V, short-circuit current density of 39.18 mA/cm2, and fill factor of 0.7390 for an optimized H2 flow rate of 2.5 sccm, showing an obvious enhancement in comparing with the conventional ITO counterpart.