Direct Current Magnetron Sputtering Method Research Articles

Electrical properties of aluminum contacts deposited by DC sputtering method for photovoltaic applications

The use of aluminum contacts is common in the process of silicon solar cells production because of low contact resistivity. It has also a great importance in thin film technology for photovoltaics, especially in copper-indium-gallium-diselenide (CIGS) devices. The final stage of CIGS cell production is the top contact deposition of high conductivity layer for lateral current collection. Such material has to be highly optically transparent as well. In order to make a contact, metal is deposited onto TCO layer with minimum shadowing to allow as much light as possible into device. The metal grid contact is being made by deposition of few microns of aluminum. The resistivity of the deposited material as well as resistance between the metal grid and TCO layer plays a great role in high quality solar cell production. This paper presents the results of four point probe conductivity analysis of Al thin films deposited by direct current (DC) magnetron sputtering method. Influence of technological parameters of the Al deposition process on sheet resistance of deposited layers has been showed. In order to obtain the lowest resistivity of the thin contact layer, optimal set of sputtering parameters, i.e. power applied, deposition time and deposition pressure was found. The resistivity of the contact between two adjacent Al metal fingers deposited onto transparent conductive Al-doped zinc oxide film has been also examined.

A novel composite hydrogen sensor based on Pd nanoclusters/TiO2 nanotube arrays

A novel composite hydrogen sensor, consisting of Pd nanoclusters/TiO2 nanotube arrays, was fabricated and evaluated at room temperature. The Pd nanoclusters layer was deposited on top surface of the nanotube arrays by using a direct current (DC) magnetron sputtering method. Resistive response of the composite sensors to 0.5% hydrogen was measured. Experimental results indicated that the Pd nanoclusters can quickly and continually form or break multiple passages by absorbing or desorbing hydrogen, so that the composite hydrogen sensors have promising hydrogen sensitivity at room temperature.

Determination of the optimum annealing temperature and time for Indium-doped SnO2 films to achieve the best p-type conductive property

This report focuses on studying and fabricating In-doped SnO2 (TIO) films following various depositing and annealing temperatures. TIO films were deposited on quartz glass substrates using a direct current (DC) magnetron sputtering method. These preferred SnO2 (101) and (211) reflections became dominant due to the substitution of Sn by In in the SnO2 host lattice. The valence state of In existing in TIO film was recorded using X-ray photoelectron spectroscopy (XPS). The p-type conductive property was found at a minimum temperature of 400 °C, and the best conductivity was achieved at the optimum annealing temperature of 550 °C for 2 h with resistivity, hole concentration, and mobility of 0.68 Ω cm, 1.13 × 1018 cm−3, and 8.13 cm2V−1s−1, respectively. Furthermore, the average transmittance of the films was above 85%. Grain shape and size were observed by scanning electron microscopy (SEM). The existence of the In3+ state in the band gap was identified using photoluminescence spectra at room temperature. The rectified characterisation revealed the behaviour of a p-TIO/n-Si heterojunction diode.

Direct growth of CuO/ITO nanowires by the vapor solid oxidation method

In this paper, we report the synthesis results of cupric oxide nanowires (NWs) on the indium tin oxide (ITO) substrate by vapor solid oxidation method. In our study, a Cu layer of thickness 1.4 µm was deposited on ITO thin film substrates through the direct current DC magnetron sputtering method. Cupric oxide NWs grew on ITO after annealing Cu/ITO substrates at the temperatures with range from 350 to 500 °C in air for 3–5 h. The received peak shift of Cu2O to CuO NW phase depending on annealing temperatures was conducted by X-ray diffraction. Chemical atomic elements were obtained from energy dispersive X-ray spectroscopy. The morphology of nanowires were investigated using scanning electron microsope (SEM). The SEM images indicated that the NWs with length about 3–3.5 µm and diameter about 100 nm grew vertically over large area.

Microstructure and He desorption behaviors of He charged FeCrNi-based films fabricated by direct current magnetron sputtering

He-charged FeCrNi-based films were prepared at different temperatures in a mixed atmosphere of He and Ar by direct-current magnetron sputtering method. X-ray diffraction and energy dispersive spectrometry analysis confirmed the typical austenitic structure of the deposited FeCrNi films and the compositions were in good accordance with 304 stainless steel target. Cross-sectional scanning electron microscopy images revealed the dense columnar nanocrystalline structure of the fabricated FeCrNi films. Nanoindentation measurements showed that the film fabricated at 300°C exhibited the highest hardness value of 11.5GPa. He desorption from FeCrNi-based films was traced by thermal desorption spectroscopy; the relatively low He desorption temperature range (150°C–450°C) implied that the charged He atoms were mainly located in interstitial sites of FeCrNi-based films.

Tuning The Crystallographic Structure And Morphology Of Nanocrystalline CaB6 Films Deposited By DC Magnetron Sputtering

Abstract Through changing the argon pressure, CaB6 films with different crystallographic orientation and morphology on glass substrates were prepared by direct current (DC) magnetron sputtering method. The film textures, crystallite sizes, composition and morphology were investigated by a spectrum of characterizing techniques in terms of X-ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive spectrometer (FESEM-EDS), atomic force microscopy (AFM), Raman shift spectroscopy. The influence of argon pressure on microstructure was studied. The average grain size increased with the argon pressure increasing from 0.8 Pa to 1.5 Pa. Meanwhile, the dominant crystal face changed from (110) to (100). Then the grain size decreased when the argon pressure increased to 2.0 Pa. The surface morphology evolved from typical cauliflower-like nanocrystalline clusters to faceted rectangular pyramids. It was found that considerable amount of argon atoms were trapped in the films. The formation process of CaB6 films was also analyzed in this paper.

Effects of Cd concentration on microstructure and optical properties of the ternary Zn1−xCdxO alloy thin films synthesized by magnetron sputtering

The ternary Zn1−xCdxO (0≤x≤1) alloy thin films were deposited on quartz substrate by the direct current (dc) reactive magnetron sputtering method. As x varied from x=0 to 0.5, the Zn1−xCdxO thin films had a hexagonal wurtzite structure of pure ZnO and highly (002) preferred orientation. The optical band-gap energies of the Zn1−xCdxO thin films were tuned from 3.24eV at x=0 to 2.04eV at x=0.5. But for the samples with x≥0.8, the Zn1−xCdxO thin films had a rock–salt structure of pure CdO and highly (200) preferred orientation. Correspondingly, the optical band-gap energies of the Zn1−xCdxO thin films decreased from 2.35eV at x=0.8 to 2.22eV at x=1, which has a little change. The variations of the band-gap energies for the thin films with hexagonal wurtzite structure were analyzed from the viewpoint of band structure.

Comparative study of amorphous indium tin oxide prepared by pulsed-DC and unbalanced RF magnetron sputtering at low power and low temperature conditions for heterojunction silicon wafer solar cell applications

Comparative study of indium tin oxide (ITO) was performed between films prepared by pulsed direct current (PDC) and radio frequency (RF) magnetron sputtering methods at low power and low temperature conditions. The best achieved film resistivity is in the range of 3–6 × 10−4 Ω cm with the highest electron carrier mobility of ∼60 cm2/V. The properties of the surface layer and the bulk material were analysed in details by means of X-ray photoelectron spectroscopy (XPS). Although there is a little difference in elemental compositions, it is revealed that the ITO's properties are directly related to the chemical bonding conditions. Owing to the fast film growth rate of PDC sputtering method, second phase Sn3O4 is formed which impedes the optical performance of the ITO films. Our observations suggest that the darkening of ITO is most likely due to the existence of Sn3O4 second phases that trapped inside of the film bulk. Besides material properties, we have demonstrated that the PDC sputtering method introduces more particle bombardment damage, while for RF sputtering the damage is mainly contributed by ultraviolet radiation emission. The major sputtering induced damage can be recovered by 15 min thermal annealing at 200 °C in air.

Effects of the thickness on the microstructure and corrosion behavior of a TiAlN film on 4140 steel

Abstract TiAlN films with thicknesses of 250, 500 and 750 nm were deposited on 4140 steel using the reactive direct current co-unbalanced magnetron sputtering method. The effects of the film thickness on the microstructure were revealed using a field emission scanning electron microscope, an image analyzer and X-ray diffraction. The results showed that grain size apparently increased when the film was at greater thicknesses whereas porosity, lattice strain and dislocation density decreased. Meanwhile, the results of anodic polarization tests in air-saturated 3.5 wt.-% NaCl solution at pH levels of 2, 7 and 10 and at 25 °C showed lower corrosion potential in thicker film, attributed to a lower ratio of grain boundary area to individual grain area. However, a more stable passive film with higher pitting potential was formed. By analyzing using X-ray absorption spectromicroscopy, oxidation of Ti into TiO2 was found on the corroded surface of TiAlN film.

Effects of annealing temperature on the properties of copper films prepared by magnetron sputtering

Copper oxide thin films were prepared by a direct-current magnetron sputtering method followed by a thermal annealing treatment at 100–500 °C. The obtained films were characterized by X-ray diffraction, UV-vis absorption spectroscopy, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. With the increase of the annealing temperature, it was found that the films transformed sequentially from amorphous to single-phase Cu (100 °C), mixed-phase of Cu and Cu2O (150 °C), single-phase Cu2O (200 °C), then to mixed-phase of Cu2O and CuO (300 °C), and finally to single-phase CuO (400–500 °C). Further analyses indicated that the Cu/Cu2O thin films and the Cu2O thin films presented no further oxidation even on the surface in air atmosphere. Additionally, the visible-light photocatalytic behavior of the copper oxide thin films on the degradation of methylene blue (MB) was also investigated, indicating that the films with pure Cu2O phase or Cu/Cu2O mixed phases have excellent photocatalytic efficiencies.

Fabrication of low phase transition temperature vanadium oxide films by direct current reactive magnetron sputtering and oxidation post-anneal method

Vanadium oxide thin films were deposited on ordinary glass substrates by direct current (DC) magnetron sputtering from a vanadium metal target and subsequent oxidation annealing. The deposition and annealing parameters were given in detail. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). The phase transitions of films were observed by measuring their electrical and optical property variations at different temperature. The results indicated that the films fabricated had a semiconductor–metal phase transition temperature of about 30°C.

Structure and optical properties of Cd-substituted ZnO (Zn1−x Cd x O) thin films synthesized by the dc reactive magnetron sputtering

The ternary Zn1−x Cd x O (x = 0, 0.2) thin films with wurtzite structure and highly (002)-preferred orientations were deposited on glass substrates by the direct current (dc) reactive magnetron sputtering method. The X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), optical absorption spectra and photoluminescence (PL) were employed to investigate the structural and the optical properties in detail. The results indicated that as x varied from x = 0–0.2, the diffraction angle of the (002) peaks decreased from ~34.36° to ~33.38° and the lattice spacing increased from 0.260 to 0.268 nm. Moreover, the optical band-gap of the Zn1−x Cd x O thin films with the wurtzite structure decreased from 3.20 eV at x = 0–2.70 eV at x = 0.2. Correspondingly, the near-band-edge PL was tuned in a wide visible region from ~393 to 467 nm. The chemical bonding states of Cd in Zn1−x Cd x O alloy thin films were examined by XPS analysis.

The Fabrication of High Resistance-Temperature-Coefficient Vanadium Oxide Film by Magnetron Sputtering Method

Direct current (DC) magnetron sputtering method was used to deposit vanadium oxide thin films on ordinary glass substrates from a vanadium metal target and a five factors four levels orthogonal experimental method was used to find the best combination of sputtering pressure, sputtering power, oxygen/argon flow ratio, substrate temperature and deposition time for fabricating high temperature coefficient of resistance (TCR) vanadium oxide film. The results indicate that a good combination of these parameters should be 1Pa, 160W, 1.5/25, 280°C and 60 minutes. And the film fabricated using this parameters combination is mainly composed of V2O5and has a resistance range of 80.3kΩ to 40kΩ while its temperature changed from 20°C to 80°C.

Investigation of resistive switching in graphite-like carbon thin film for non-volatile memory applications

Graphite-like carbon films were deposited on Al/SiO2/Si substrates by using Direct Current magnetron sputtering method. Stable and reliable bipolar resistive switching (RS) characteristics were observed in Cu/a-C/Al/SiO2/Si multi-layer structures. An ON/OFF ratio of about 3, a retention time of more than 105 s, and switching threshold voltages of less than 3 V were achieved. I–V properties in both low resistance state and high resistance state can be well explained by the space charge limited current model. The observed RS behaviors are attributed to the electron trapping and detrapping at deep level defects in a-C films.

Influence on optical properties and switching durability by introducing Ta intermediate layer in Mg–Y switchable mirrors

Magnesium–yttrium alloy switchable mirrors capped with a Pd layer with a thickness of 7.5nm have been shown to have a high switching durability of over 10,000 cycles between reflective and transparent states. However, the durability decreased considerably when the Pd thickness was decreased to improve the transmittance in the transparent state. Switchable mirrors with a thin Ta intermediate layer inserted between Mg–Y alloy layer and thinner Pd layers were then prepared by a direct-current magnetron sputtering method, and the optical switching durability was studied. Such a mirror capped by a Pd layer with a thickness of 3nm had a high switching durability of over 10,000 cycles, although a mirror without the Ta intermediate layer capped by a Pd layer with the same thickness never changed from the reflective to the transparent state. Owing to the decrease of the Pd thickness from 7.5 to 3nm, the visible transmittance in the transparent state increased, respectively, from 32% to 44% with high switching durability. The results of X-ray photoemission spectroscopy and transmission electron microscopy showed that the inserted Ta layer fully inhibits alloying between the Pd and Mg–Y layers, and that the Pd existed at the surface region and scarcely diffused into the Ta and Mg–Y layers even after switching of 10,000 cycles. Because alloying is one of the main reasons for the reduction in durability with decreasing Pd thickness, the prevention of alloying is expected to cause high switching durability.

Influence of substrate temperature on structural and optical properties of ZnCdO thin films deposited by dc magnetron sputtering

Zn1−xCdxO (x=0.2) thin films were deposited on glass substrates at different substrate temperatures (Ts) by the direct current (dc) reactive magnetron sputtering method. The influence of substrate temperature on structural and optical properties was investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), optical absorption spectra and Raman scattering in detail. Results indicated that all the obtained Zn1−xCdxO (x=0.2) thin films were of highly (002)-preferred orientation and possessing the hexagonal wurtzite structure of pure ZnO, the crystalline quality first was improved and then deteriorated as the Ts increased up from 25°C to 600°C, when Ts is 550°C, the film had the best crystalline quality. Meanwhile, the optical band gap of Zn1−xCdxO films was tuned from 2.728 to 2.782eV, which was attributed to the variation of the compressive stress and the Cd re-evaporation in the films. In addition, the residual stress and defects of films were evaluated from Raman spectroscopy.

Experimental investigation on the growth rate of Cu nano-thin films by DC and RF magnetron sputtering methods

The growth rate of the Cu nano-thin film was investigated based on the magnetron sputtering method under different process parameters and different sputtering method. Firstly, some samples of Cu nano-thin films were sputtered on the glass substrate by changing different sputtering power at the direct current (DC) magnetron sputtering method. Secondly, some Cu nano-thin film samples were prepared by using the DC magnetron sputtering method and radio frequency (RF) magnetron sputtering methods. The thickness of the Cu nano-thin film was test by the film thickness gauge, and then the growth rate of the Cu nano-thin film was obtained. These results show that the sputtering power is very important for the growth rate. The growth rate of the Cu nano-thin film increases with the increase of the sputtering power at the DC magnetron sputtering method; the growth rate of the Cu nano-thin film prepared under the DC magnetron sputtering method is about ten times of that prepared under the RF magnetron sputtering method.

Preparation of Amorphous Coatings of AlFeCoNiCuZrV Alloy by Direct Current Magnetron Sputtering Method

Preparation of Amorphous Coatings of AlFeCoNiCuZrV Alloy by Direct Current Magnetron Sputtering Method

Pd distribution of switchable mirrors based on Mg–Y alloy thin films

Pd-capped magnesium–yttrium alloy switchable mirrors were found to have high switching durability of over 10,000 cycles between reflective and transparent states. However, the durability decreased with the decreasing Pd thickness. Switchable mirrors with various Pd thicknesses were then prepared by a direct-current magnetron sputtering method, and the degradation in durability was studied by observing the distribution of each element of the switchable mirrors from the film surface to the substrate. X-ray photoemission spectroscopy and transmission electron microscopy showed that Pd with a short sputtering time (corresponding to layer thickness of 3nm) resulted in surface oxidation of Mg and Y, and no Pd was present at the surface. The deposited Pd was alloyed with the Mg–Y layer and after taking the sample out from the vacuum chamber a Pd-rich layer appeared between the surface oxides and the Mg–Y layers. With increasing deposition time, a Pd layer was formed on the oxide layer and the Pd layer thickness increased. The mirror with switching durability of over 10,000 cycles had a sufficiently thick Pd top layer of ~7nm and a very thin oxide layer. This thick Pd layer is believed to be the reason for the high switching durability.

Protection Effect of ZrO<SUB>2</SUB> Coating Layer on LiCoO<SUB>2</SUB> Thin Film Fabricated by DC Magnetron Sputtering

Bare and ZrO2-coated LiCoO2 thin films were fabricated by direct current magnetron sputtering method on STS304 substrates. Deposited both films have a well-crystallized structure with (003) preferred orientation after annealing at 600 degrees C. The ZrO2-coated LiCoO2 thin film provide significantly improved cycling stability compared to bare LiCoO2 thin film at high cut-off potential (3.0-4.5 V). The improvement in electrochemical stability is attributed to the structural stability by ZrO2 coating layer.