Sputtering Pressure Research Articles

Deposition-rate controlled nitrogen-doping into cuprous oxide and its thermal stability

Cuprous oxide has important applications from photovoltaic devices to photocatalysis and nitrogen-doping can improve the p-type conductivity of cuprous oxide. Here, phase-pure cuprous oxide thin films are prepared by sputtering a copper target in the atmosphere of Ar, O2 and N2 with the sputtering pressure varying from 0.6 Pa–3.0 Pa. The samples deposited at 0.6 Pa is also annealed in the flow of Ar or Ar plus N2. The results show that sputtering pressure below 1.0 Pa results in higher deposition rate and more nitrogen incorporation into cuprous oxide while sputtering pressure of 3.0 Pa leads to lower deposition rate and no nitrogen doping though the gas flow rates are the same. In nitrogen-doped Cu2O, nitrogen exists as β-N (atomic nitrogen), α-N2 (-N=N-) and γ-N2 (NN). Annealing completely removes β-N and partially turns α-N2 into γ-N2. Nitrogen-doped cuprous oxide has smaller resistivity and larger hole density than undoped samples. The longest time for the absorbed nitrogen molecules to stay on the copper position is estimated to be 8.45 × 10−7 s. Annealing has little effect on the electrical and optical properties of nitrogen-doped cuprous oxide though it induces a weak decomposition.

Scratch behavior and FEM modelling of Cu/Si(100) thin films deposited by modulated pulsed power magnetron sputtering

A series of copper thin films on Si(100) substrate were deposited using the modulated pulsed power magnetron sputtering under a sputtering pressure from 0.11 to 0.70 Pa. The scratch behavior of Cu/Si(100) thin films was characterized by the critical loads (Lc1–4) with the aid of finite element method (FEM) simulation. Increasing the sputtering pressure, surface morphology became rougher and the cross-sectional pattern transformed from compact fine granular to coarse and crack visible columnar structure. The Cu thin films scratched were continuous and comparative intact at 0.11 Pa which occurred to be with the highest critical loads, then gradually went to vast delamination initiated at 0.30 Pa with the Lc decreasing accordingly. The maximum principal stress (σ1) calculated by FEM was employed to evaluate the transition of critical loads Lc1–Lc4 using the typical stress concentration zones A, B and C which were the zones under, around and at the sides of the scratch tip, respectively. For the Cu/Si(100) thin films with strong adhesion, the Lc1 and Lc2 were evaluated through the migration of σ1 peak from the zone B to C, while the Lc3 and Lc4 were associated with stress accumulation at the zone C and A. The scratch behavior of Cu/Si(100) thin films was quantitatively expressed with the aid of FEM simulation.

Influence of pressure on the properties of AlN deposited by DC reactive magnetron sputtering on Si (100) substrate

Preferred (002)-oriented aluminium nitride (AlN) films by direct-current (DC) magnetron sputtering on Si (100) substrate were prepared at various deposition pressure (0.12-0.5 Pa). The influence of pressure on the surface morphology, crystal structure and optical properties of AlN thin films was discussed the with the methods of X-ray diffraction, atomic force microscopy and stress analyser, respectively. Optical properties were studied by ellipsometer and Fourier transform infrared spectrometer. It was observed that the AlN films tended to be preferred (002)-oriented when the pressure was decreased and the value of full width at half maximum is 0.325° when the pressure was kept at 0.12 Pa. the tensile stress, refractive index, and the density of Al-N bonds decreased with increasing the sputtering pressure from 0.12 to 0.5 Pa. This work demonstrated the influence of sputtering pressure on the structural and optical properties of the AlN films deposited on Si (100) substrate, the gallium nitride epitaxial film on Si (100) substrate was expected to be realised using sputtered AlN as the buffer layer.

Impact of deposition pressure and two-step growth technique on the photoresponsivity enhancement of polycrystalline BaSi2 films formed by sputtering

We investigate the influence of deposition pressure in the range 0.25–1.0 Pa on the photoresponsivity of 200 nm thick BaSi2 films grown by sputtering at 600 °C. BaSi2 films formed at 0.8 Pa exhibit a high photoresponsivity. The deposited Ba-to-Si atomic ratio depends significantly on the sputtering pressure. That’s why the pressure influences the photoresponsivity. BaSi2 films grown by a two-step growth technique show much higher photoresponsivity almost equivalent to those grown by molecular beam epitaxy. The photoresponsivity reaches 0.75 A W−1 at 2.0 eV at a bias voltage of 0.5 V applied between the top and bottom electrode.

Study on the Adhesion Force Between Ga-Doped ZnO Thin Films and Polymer Substrates.

Flexible Ga doped ZnO (GZO) transparent conductive thin films were prepared on polycarbonate (PC) substrates at room temperature by magnetron sputtering. The adhesive property between the GZO film and the PC substrate was investigated quantitatively by the scratch test, which is designed for the quantitative assessment of the mechanical integrity of coated surfaces. The effect of the sputtering pressures on the adhesion forces for the GZO films was investigated. When the sputtering pressure varied from 0.2 to 0.5 Pa, no obvious adhesion force alteration was observed. However, when the sputtering pressure was increased to 0.7 Pa, the adhesion force was decreased. The lowest square resistance of the GZO film was 18.6 Ω/sq. Regardless of the sputtering pressure, the transmittance in the visible light was about 90%. When the sputtering pressure was 0.4 Pa, the optimal figure of merit (ΦTC) was 2.5×10-2 Ω-1, indicating that the optimal pressure was 0.4 Pa.

Thickness dependent chemical and microstructural properties of DC reactive magnetron sputtered titanium nitride thin films on low carbon steel cross-section

Polished samples of low carbon steel (LCS) rod cross-sections were sputtered with different thicknesses of TiNx thin film using DC reactive magnetron sputtering technique. While other process parameters such as target power (200W), substrate position (150mm) and sputtering pressure (1.33Pa) were kept constant during the deposition, the deposition time was varied from 5 to 20min. Physical and chemical characterizations of the samples were done using Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and optical microscopy. Vickers micro-hardness tester was used for the hardness test. The optimum value of the Vickers hardness was found to be 267.9 for the film deposited at 20min. The inter-planar spacing was found to be from 2.0362Å to 2.0890Å, while corresponding lattice parameter was calculated to be from 4.0724Å to 4.1780Å. Scanning electron microscopy observation of the films gave an indication of fine-grained microstructure, which confirms the good adhesion and hardness properties of titanium nitride layer on the LCS substrate. The XRD spectra show that the multiphase reflections TiO2 (110) and TiN (111) for thinner film samples which shift to a preferred orientation (200) for thicker films, indicating a largely TiNx phase. This strongly suggest remarkable changes in crystal orientations of the TiNx films with deposition time. Ion beam (RBS) results showed increase in amount of nitrogen contents (47–64%) in TiNx films with thickness and deposition time.

Al-doping and Properties of AZO Thin Films Grown at Room Temperature: Sputtering Pressure Effect

Aluminum zinc oxide (AZO) thin films were synthesized on glass substrates by radio frequency (rf) magnetron sputtering from a metallic Zn-Al (5 at. %) target at room temperature. The morphological, structural, electrical and optical properties of the films were studied as a function of the sputtering pressure, which was varied from 0.1 to 6.7 Pa. X-ray diffraction (XRD) analyses revealed that the films obtained were polycrystalline, having a hexagonal wurtzite structure with a preferential orientation in the (002) plane. In addition, the crystallite size increased as a function of sputtering pressure. Owing to the re-sputtering of the Zn atoms from the growing film, the aluminum concentration presented a maximum value of 13 at. %. At pressures close to 0.16 Pa, we obtained films with values of electrical resistivity and mobility of 2.8 10-3 Ω cm and 17 cm2/Vs, respectively. Finally, our results indicate that the structure zone diagram proposed by Thornton and later modified by Kluth does not fully predict the structural/morphological behavior of the AZO films, since plasma interactions must also be taken into account. With the methodology used, transparent conductive electrodes can be deposited on substrates at low temperatures.

하지층 Cr의 스퍼터링 압력을 달리하여 제작한 Cr/CoSm/Cr 자성막의 자기상호작용이 자기역전부피에 끼치는 영향

하지층 Cr의 스퍼터링 압력을 달리하여(7~10 mTorr) 제작한 Cr/CoSm/Cr 자성막의 자기상호작용이 자기역전부피에 끼치는 영향을 조사하였다. 연구에 사용된 모든 Cr/CoSm/Cr 자성막의 자기상호작용 기구는 쌍극자 상호작용이었으며, 낮은 스퍼터링 압력에서 제작한 시료일수록 쌍극자 상호작용이 더 강했다. 또한 각 시료의 최대 쌍극자 상호작용이 일어난 자기장(HSUBΔM/SUB)은 보자력 (HSUBc/SUB)보다 컸다. 자기역전부피는 쌍극자 상호작용이 강한 시료일수록 더 컸으며, 각 시료의 자기역전부피는 HSUBΔM/SUB 영역에서 최대를 보이다가 더 큰 자기장 영역에서는 감소하는 경향을 보였다. 따라서 쌍극자 상호작용의 세기가 역전부피의 증감에 크게 관련되는 것으로 판단된다.

Effects of Sputtering Pressure on (ZnO)<sub>x</sub>(InN)<sub>1-x</sub> Crystal Film Growth at 450°C

We studied effects of sputtering pressure on growth of (ZnO)x(InN)1-x crystal films deposited at 450°C by rf magnetron sputtering. Epitaxial growth of (ZnO)x(InN)1-x films was realized on single-crystalline ZnO template. X-ray diffraction measurements show that full width at half maximum of the rocking curves from the (101) plane of the films reaches minimum value of 0.11º at 0.5 Pa. The sputtering gas pressure is a key tuning knob for controlling the crystal quality of ZION films.

Fabricating ZnSnN2 with cosputtering

The deposition of ZnSnN2 by co-sputtering was studied systematically. Different deposition parameters, including substrate temperatures, N2 flow rates and different work pressure etc. were tried and the structural, optical and electrical properties were studied. The results show that the deposition parameters to fabricate ZnSnN2 are relatively wide. The suitable substrate temperature to obtain polycrystalline ZnSnN2 is around 350 °C when other parameters are kept constant. Relatively larger N2 flow rate can suppress the formation of metallic phase such as Sn and favour the deposition of ZnSnN2 with relatively pure phase, with other parameters to be constant. The addition of the substrate bias voltage or a relatively lower power of the Sn target is harmful to the film crystallization of ZnSnN2. The samples are considered to be wurtzite due to the absence of the orthorhombic (110) and (011) peaks at 20°–22°. The hexagonal lattice constants a and c are about 3.36–3.40 Å and 5.49 Å, respectively. The sputtering pressure can affect the structural and electrical properties of ZnSnN2. ZnSnN2 prepared at larger work pressure such as 7.0 Pa has a lower electron density (6.72 × 1019 cm−3) and a higher mobility (24.3 cm2 V−1 s−1) as compared with those prepared at 1.0 and 3.0 Pa.

Magnetic properties of RF-sputtered NiO and Ni0.8Fe0.2O1-δ samples grown on SiO2/Si substrates

ABSTRACTMagnetic properties of RF (Radio Frequency)-sputtered NiO and Ni0.8Fe0.2O1-δ films made at low or high oxygen (O) sputtering pressures were studied and discussed. The X-ray diffraction pattern shows that all samples have a NaCl-type structure. The magnetic properties were measured as a function of magnetic field at different temperatures using the PPMS Model-6000. All samples contain a small magnetic moment resulting in a saturation magnetisation of 1–5 emu/cm3. A hysteresis curve at fields below 500 oersted (Oe), and a high-field magnetic slope were observed in all samples. Low-field hysteresis and high magnetic slope depend on the temperature. For a low O flow sputtered sample, the high-field slope increases with increasing temperature, and for a high O flow sputtered sample, the high-field slope decreases with increasing temperature. The low-field hysteresis increases for low O flow sputtered samples but increases for high O flow sputtered samples.

Controlling morphology and texture of sputter-deposited Pd films by tuning the surface topography of the (Ti) adhesive layer

In this work, the effect of the deposition parameters of a magnetron sputtered Ti adhesive intermediate layer on the morphology and hydrogen absorption properties of thin Pd films of about 100 nm was investigated. The insertion of an adhesive layer between a Pd film and a rigid substrate usually suppresses or reduces hydrogen absorption. In this study, it is shown that by tuning the surface topography of the intermediate layer the morphology, crystallographic texture and hydrogen absorption properties of the Pd film can be controlled. The surface topography of the Ti layer was characterized using atomic force microscopy. The surface topography strongly depends on the Ti deposition conditions and can vary from widely spread large islands to densely packed small-grained islands depending on thickness (between 1 and 6 nm) and sputter pressure (0.4 and 3 Pa). TEM and XRD analysis led to the conclusion that rough Ti intermediate layers result in Pd films with an open columnar structure with small voids, and a weak and broad (111) texture. Smooth Ti intermediate layers promote the formation of Pd films with a dense columnar structure with fewer voids, and a strong and sharp (111) texture. Changes in the Pd adatom surface diffusion and shadowing effects are the main cause of the observed differences. Pd films with an open columnar morphology and weaker texture show better hydrogen absorption properties with respect to absorption capacity and kinetics of the films with dense columnar morphology. By tuning the surface topography of the Ti adhesive layer, Pd films with controlled morphology and texture can be prepared such that no delamination from the substrate occurs without compromising on absorption properties.

Optical and structural properties of TiO2 as intermediate buffer layer prepared by DC reactive magnetron sputtering for solar cells

A series of titanium oxide thin films was synthesized through direct current magnetron sputtering on glass and silicon substrates using various process parameters. Initially, the morphology, the cross-section and layer composition of the samples was examined. Additionally, the transmission spectra of the thin films were measured. Transmittance and reflection spectra of UV–vis analysis were utilized to calculate the optical band gap, extinction coefficient, Urbach energy, and absorption coefficient of the oxidized layers. Two of the manufactured samples with the highest sputtering pressure were highly optically transparent (up to 100% and 90%) in the region of 400 to 1000 nm. The mean absorption coefficient ranged from ·105 to 4·105 1/cm, the extinction coefficient ranged between 0 and 10, and Urbach energy ranged between 3.1 and 3.35 eV. Reflectance ranged from 10% to 50% in the region from 500 to 2500 nm. The process parameters of the TiO2 structure were verified to improve its quality as a buffer layer. After this preliminary analysis, we propose the most promising and future-oriented solutions for photovoltaic applications.

Tuning the photoluminescence, conduction mechanism and scattering mechanism of ZnSnN2

The high electron concentration and low mobility of ZnSnN2 hinder its potential applications in photocatalytic and optoelectronic devices. To reveal the mechanism, herein, ZnSnN2 thin films were prepared under different sputtering pressure. The results show that impurity band conduction, an electron density of above 1020cm−3 and a mobility of 2 cm2 V−1 s−1 dominated by variable-range hopping are observed in samples prepared at lower sputtering pressure, due to the unintentional incorporation of substitutional oxygen which is from residual vapour and which substitutes nitrogen, while conduction band conduction, an electron density of 1019 cm−3, a mobility of 24 cm2 V−1 s−1 limited by ionized impurity scattering and self-compensation ratio as well as an interband direct recombination emission are found in samples prepared at higher sputtering pressure, due to the decrease in substitutional oxygen doping.

Preparation of highly visible transparent ZnO/cellophane UV-shielding film by RF magnetron sputtering

A novel UV-shielding film created by sputtering ZnO film onto a renewable and biodegradable cellophane film is proposed. The dependence of the optical properties of the ZnO/cellophane hybrid film on the sputtering power, pressure, and film thickness was studied systematically. A high crystalline quality ZnO film with preferred [002] orientation was prepared on a cellophane substrate for the first time. Unlike conventional UV-shielding films consisting of nanostructures and synthetic polymers, ZnO/cellophane hybrid film can possess high visible light transparency and excellent UV-shielding capacity at the same time. The improved performance can be attributed to the high crystalline quality and the antireflection effect of the ZnO film. A typical hybrid film exhibits a UV-shielding ratio of 96.5% while exhibiting a transmittance of visible light of over 80%. ZnO/cellophane hybrid films can be applied in a vast range of UV-shielding applications, such as sunburn protection and short-wave radiation protection in the laboratory.

Sterilization for Bacillus Subtilis var. natto by Low Pressure Sputtering and Laser Ablation Plasma using Metal Powder Target

Sterilization for Bacillus Subtilis var. natto by Low Pressure Sputtering and Laser Ablation Plasma using Metal Powder Target

Development of nanostructured nickel oxide thin film matrix by rf sputtering technique for the realization of efficient bioelectrode

In the present work, RF magnetron sputtering technique has been exploited with varied deposition parameters (optimized parameters: sputtering pressure = 20 mT, 100% O2 gas ambient, without any substrate heating) to develop nanostructured NiO thin film matrix with increased surface roughness (5.09 nm) and good charge transfer properties for efficient detection of cortisol. Electrochemical and electrical studies have been performed to determine charge communication characteristics and conductivity of the prepared NiO thin film that could yield enhanced biosensing response properties. The biosensing response has been studied on the optimized parameters using cortisol as a test analyte and a relatively high sensing response of 14 μA (ug/mL)−1 has been obtained for the optimized NiO matrix-based electrodes (Cortisol-Ab/NiO/ITO).

Microstructure‐Mechanical Property Correlation in Size Controlled Nanocrystalline Molybdenum Films

The authors report on the microstructure, crystallography, and mechanical properties of size controlled nanocrystalline (nc) molybdenum (Mo) films deposited by sputtering. The nc‐Mo films of ≈100 nm thick with a variable microstructure are deposited under variable argon (Ar) sputtering pressure (PAr), which is varied in the range of 3–25 mTorr. X‐ray diffraction analyses indicate that the nc‐Mo films exhibit (110) preferential growth. However, the crystal‐quality degradation occurs for Mo films deposited at higher PAr due to difference in the adatom mobility. The average crystallite size (d) of the nc‐Mo films is in the range of 5–20 nm; size decreases with increasing PAr. The effect of sputtering pressure is significant on the microstructure, which in turn influences the mechanical characteristics of Mo films. The hardness (H) and modulus of elasticity (Er) of nc‐Mo films deposited at lower PAr are higher but decreases continuously with increasing PAr. Under optimum sputtering conditions, the best mechanical characteristics obtained for Mo films are: H = 25 GPa, Er = 360 GPa, H/Er = 0.07, and H3/ = 0.13 GPa. A size‐microstructure‐mechanical property correlation in nc‐Mo films is derived based on the results presented and discussed.

Detailed optical analysis of 100 MeV Ni7+ ion irradiated WO3 thin films using Surface Plasmon Resonance

Modifications in the structural, optical properties and surface morphology of RF sputtered WO3 thin films after irradiation with 100 MeV Ni7+ ions have been reported in the present article. The WO3 thin films were deposited at different sputtering pressures (10–50 mTorr). Despite the grain growth due to irradiation, no structural phase transformation has been observed for the WO3 thin films deposited up to 30 mTorr growth pressure. However, complete amorphization post irradiation was detected for the orthorhombic WO3 thin film grown at 50 mTorr sputtering pressure. AFM images indicated that the pristine WO3 thin film consists of uniform grains having smooth surface morphology. Upon irradiation, grain size increased consistently along with increase in surface roughness (Rq) at all sputtering pressures. The root mean square roughness (Rq) estimated from AFM analysis increased from 1.76 nm in pristine film to 9.89 nm in response to irradiation at a fluence of 1 × 1012 ions cm−2. A systematic decrease in optical band gap has been observed with irradiation, which can be correlated with Ni7+ ion induced mid-gap and near band edge defect states. Surface Plasmon Resonance (SPR) technique has been recognized as an appropriate tool to study the optical properties of pristine and irradiated WO3 thin films. SPR reflectance curves were recorded in angular interrogation mode at 633 nm excitation wavelength for pristine and Ni7+ ions irradiated WO3 films deposited at varying deposition pressure.

Wide Bandgap Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering at Room Temperature

Room temperature RF magnetron sputtering deposition of Zinc Oxide thin films on a glass substrate was carried out by varying deposition parameters such as sputtering pressure, target-to-substrate distance, and RF power. The as-deposited film at 75 W, sputtering pressure of 9.8 mbar and a target-to-substrate distance of 104 mm has showed a band gap of 3.31 eV and RMS surface roughness of 7.1 nm. Electrical characterization and UV–VIS results reveal its high resistivity (1.3 × 107 Ω-cm) and transparency >86% in a wide optical range (494–1100 nm). This film could be used as a buffer layer of CIS solar cells, SAW, and other similar thin film devices over a flexible substrate.