Ferromagnetism in Eu-doped ZnO films deposited by radio-frequency magnetic sputtering

This paper reports that Eu-doped ZnO films were successfully deposited on silicon (100) by radio-frequency magnetic sputtering. The x-ray diffraction patterns indicate that Eu substitutes for Zn in the lattice. Ferromagnetic loops were obtained by using superconducting quantum interference device at 10 K and room temperature. No discontinuous change was found in both of the zero-field-cooled and field-cooled curves. The observed ferromagnetism in Eu-doped ZnO can be attributed to a single magnetic phase. The saturation magnetisation decreased remarkably for the Eu-doped ZnO prepared by introducing 5% of oxygen in the sputtering gas or by the post annealing in O2, suggesting that the defects play key roles in the development of ferromagnetism in Eu-doped ZnO films.     

Investigation of magnetic properties for oblique deposited granular films by magnetic field annealing

A series of (Fe₅₇Co₂₄Ni₄Nb₂B₁₃)_x-(SiO₂)_1−x nano-granular thin films were fabricated by magnetron sputtering with different oblique incidence angle θ and excellent soft magnetic properties are achieved. Based on the results of magnetic field anneal at different temperature T_a, it is evidenced that orientation of atomic pairs contributes to the annealing treatment, and could manipulate magnetic anisotropy. The damping coefficient α decreases with increasing angle θ and this is ascribed to the anisotropy dissipation.     

溅射功率对直流磁控溅射Ti膜结构的影响

 采用直流磁控溅射方法制备了纯Ti膜,研究了不同功率下Ti膜的沉积速率、表面形貌及晶型结构,并对其应力进行了研究。研究表明：薄膜的沉积速率随溅射功率的增加而增加,当溅射功率为20 W时,原子力显微镜(AFM)图像显示Ti膜光洁、致密,均方根粗糙度最小可达0.9 nm。X射线衍射(XRD)分析表明薄膜的晶体结构为六方晶型,Ti膜应力先随溅射功率增大而增大,在60 W时达到最大值（为945.1 MPa）,之后随溅射功率的增大有所减小。     

溅射功率对直流磁控溅射Ti膜结构的影响

采用直流磁控溅射方法制备了纯Ti膜,研究了不同功率下Ti膜的沉积速率、表面形貌及晶型结构,并对其应力进行了研究。研究表明：薄膜的沉积速率随溅射功率的增加而增加,当溅射功率为20 W时,原子力显微镜(AFM)图像显示Ti膜光洁、致密,均方根粗糙度最小可达0.9 nm。X射线衍射(XRD)分析表明薄膜的晶体结构为六方晶型,Ti膜应力先随溅射功率增大而增大,在60 W时达到最大值（为945.1 MPa）,之后随溅射功率的增大有所减小。     

溅射功率对Mo薄膜微结构和性能的影响

实验采用直流磁控溅射沉积技术在不同溅射功率下制备Mo膜,研究了不同溅射功率下Mo膜的沉积速率、表面形貌及晶型结构,并对其晶粒尺寸和应力进行了研究。利用原子力显微镜观察样品的表面形貌发现随着溅射功率的增加,薄膜表面粗糙度逐渐增大。X射线衍射分析表明薄膜呈立方多晶结构,晶粒尺寸为14.1～17.9 nm;应力先随溅射功率的增大而增大,在40 W时达到最大值(2.383 GPa),后随溅射功率的增大有所减小。     

溅射功率对Mo薄膜微结构和性能的影响

 实验采用直流磁控溅射沉积技术在不同溅射功率下制备Mo膜,研究了不同溅射功率下Mo膜的沉积速率、表面形貌及晶型结构,并对其晶粒尺寸和应力进行了研究。利用原子力显微镜观察样品的表面形貌发现随着溅射功率的增加,薄膜表面粗糙度逐渐增大。X射线衍射分析表明薄膜呈立方多晶结构,晶粒尺寸为14.1～17.9 nm;应力先随溅射功率的增大而增大,在40 W时达到最大值(2.383 GPa),后随溅射功率的增大有所减小。     

Effect of annealing on the properties of N-doped ZnO films deposited by RF magnetron sputtering

N-doped ZnO films were deposited by RF magnetron sputtering in N₂/Ar gas mixture and were post-annealed at different temperatures (T_a) ranging from 400 to 800 °C in O₂ gas at atmospheric pressure. The as-deposited and post-annealed films were characterized by their structural (XRD), compositional (SIMS, XPS), optical (UV-vis-NIR spectrometry), electrical (Hall measurements), and optoelectronic properties (PL spectra). The XRD results authenticate the improvement of crystallinity following post-annealing. The weak intensity of the (0 0 2) reflection obtained for the as-deposited N-doped ZnO films was increased with the increasing T_a to become the preferred orientation at higher T_a (800 °C). The amount of N-concentration and the chemical states of N element in ZnO films were changed with the T_a, especially above 400 °C. The average visible transmittance (400-800 nm) of the as-deposited films (26%) was increased with the increasing T_a to reach a maximum of 75% at 600 °C but then decreased. In the PL spectra, A⁰X emission at 3.321 eV was observed for T_a = 400 °C besides the main D⁰X emission. The intensity of the A⁰X emission was decreased with the increasing T_a whereas D⁰X emission became sharper and more optical emission centers were observed when T_a is increased above 400 °C.     

Growth, structural, and magnetic properties of iron nitride thin films deposited by dc magnetron sputtering

FeN thin films were deposited on glass substrates by dc magnetron sputtering at different Ar/N₂ discharges. The composition, structure and the surface morphology of the films were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and atomic force microscopy (AFM). Films deposited at different nitrogen pressures exhibited different structures with different nitrogen contents, and the surface roughness depended on the mechanism of the film growth. Saturation magnetization and coercivity of all films were determined using superconducting quantum interference device, which showed that if N₂/(Ar+N₂) flow ratio was equal to or larger than 30% the nonmagnetic single-phase γ″-FeN appeared. If N₂/(Ar+N₂) flow ratio was less than 10%, the films consisted of the mixed phases of FeN_0.056 and γ′-Fe₁₆N₂, whose saturation magnetizations were larger than that of -Fe. If N₂/(Ar+N₂) flow ratio was 10%, the phases of γ′-Fe₄N and -Fe₃N appeared, whose saturation magnetizations were lower than that of -Fe.     

The electromagnetic shielding of Ni films deposited on cenosphere particles by magnetron sputtering method

Ni-coated cenosphere particles were successfully fabricated by an ultrasonic-assisted magnetron sputtering equipment. Their surface morphology and microstructure were analyzed using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). FE-SEM results indicate that the Ni films coated by magnetron sputtering are uniform and compact. Ni film uniformity was related with the sputtering power and a large uniform film could be achieved at lower sputtering power. XRD results imply that the Ni film coated on cenospheres was a face-centered cubic (fcc) structure and the crystallization of film sample increases with increasing the sputtering power. The electromagnetic interference (EMI) shielding effectiveness (SE) of Ni-coated cenosphere particles were measured to be 4-27 dB over a frequency range 80-100 GHz, higher than those of uncoated cenosphere particles. The higher sputtering power and Ni film thickness are the higher EMI SE of the specimens. Ni-coated cenosphere particles are most promising alternative candidates for millimeter wave EMI shielding due to their lightweight, low cost, ease of processing, high floating time, good dispersion and tunable conductivities as compared with typical electromagnetic wave countermeasure materials.     

Indium zinc oxide thin films deposited by sputtering at room temperature

The deposition of amorphous indium zinc oxide (IZO) thin films on glass substrates with n-type carrier concentrations between 10¹⁴ and 3 × 10²⁰ cm⁻³ by sputtering from single targets near room temperature was investigated as a function of power and process pressure. The resistivity of the films with In/Zn of ∼0.7 could be controlled between 5 × 10⁻³ and 10⁴ Ω cm by varying the power during deposition. The corresponding electron mobilities were 4-18 cm² V⁻¹ s⁻¹.The surface root-mean-square roughness was <1 nm under all conditions for film thicknesses of 200 nm. Thin film transistors with 1 μm gate length were fabricated on these IZO layers, showing enhancement mode operation with good pitch-off characteristics, threshold voltage 2.5 V and a maximum transconductance of 6 mS/mm. These films look promising for transparent thin film transistor applications.     

GaN films deposited by middle-frequency magnetron sputtering

GaN films were deposited on Si (111) substrates by middle-frequency magnetron sputtering. X-ray diffraction revealed preferential GaN (0 0 0 2) orientation normal to the substrate surface for all the films deposited. The diffraction intensity and N contents were found to depend strongly on the total gas pressure. Good quality films were only obtained at pressures in the range of 0.4-1.0 Pa. Little diffraction of GaN (0 0 0 2) could be observed either at total pressures below 0.4 Pa or above 1.0 Pa. The GaN films produced under the optimized conditions have an N:Ga ratio of 1:1 as determined by energy-dispersive X-ray spectroscopy.     

Formation of textured Ni(200) and Ni(111) films by magnetron sputtering

The effect of the working gas pressure (P ≈ 1.33–0.09 Pa) and the substrate temperature (T_s ≈ 77–550 K) on the texture and the microstructure of nickel films deposited by magnetron sputtering onto SiO₂/Si substrates is studied. Ni(200) films with a transition type of microstructure are shown to form at growth parameters P ≈ 0.13–0.09 Pa and T_s ≈ 300–550 K, which ensure a high migration ability of nickel adatoms on a substrate. This transition type is characterized by a change of the film structure from quasi-homogeneous to quasi-columnar when a film reaches a critical thickness. Ni(111) films with a columnar microstructure and high porosity form at a low migration ability, which takes place at P ≈ 1.33–0.3 Pa or upon cooling a substrate to T_s ≈ 77 K.     

退火处理对磁控溅射制备LaCoO_3薄膜性能的影响

采用磁控溅射法在硅衬底上制备了LaCoO_3(LCO)薄膜,研究了退火温度对LCO薄膜组织结构、表面形貌及热电特性的影响,并利用X射线衍射仪、原子力显微镜(AFM)、激光导热仪等对LCO薄膜的晶体结构、表面形貌、热扩散系数等进行测量与表征.结果表明:退火温度对LCO薄膜的结晶度、晶粒尺寸和薄膜表面形貌都有较大影响;退火前后LCO薄膜的热扩散系数都随温度的升高而减小,且变化速率逐渐减缓; LCO薄膜的热扩散系数随退化温度的升高先增大后减小.LCO薄膜经过700℃退火后得到最佳的综合性能,其薄膜表面致密、平整,结晶质量最好,热扩散系数最小,热电性能最好.     

Cuprite, paramelaconite and tenorite films deposited by reactive magnetron sputtering

Copper oxides films (Cu₂O, Cu₄O₃ and CuO) have been deposited by magnetron sputtering of a copper target in various Ar–O₂ reactive mixtures. The films are characterized by X-ray diffraction, scanning electron microscopy, four-point probe method and UV-Vis spectrometry. The three defined compounds in the Cu---O binary system can be deposited by varying the oxygen flow rate introduced into the reactor. All the films are crystallized with a mean crystal size ranging from 10 to about 35 nm. They are highly resistive and present a direct optical band gap higher than 2 eV. The application of a bias voltage during the deposition phase modifies the texture of the Cu₂O films and also induces a preferential resputtering of oxygen from the Cu₄O₃ ones. This resputtering phenomenon leads firstly to the occurrence of the cuprite phase mixed with the paramelaconite one and secondly to the amorphisation of the films. Finally, the thermal stability in air of cuprite, paramelaconite and tenorite films has been investigated. The results show that the stability of Cu₂O and Cu₄O₃ films in air is influenced by the thickness and/or the texture of the films. Tenorite films with a low optical band gap (1.71 eV) can be formed after air annealing at 350 °C of an unbiased cuprite film.     

溅射制备非晶氮化镓薄膜的光学性能

采用直流磁控溅射方法在不同的氩气-氮气（Ar-N₂）气氛中制备了非晶氮化镓（a-GaN）薄膜. X射线衍射分析（XRD）和拉曼光谱（Raman）表明薄膜具有非晶结构. 通过椭偏光谱（SE）得到薄膜的折射率和厚度都随着氩气分量的增多而增大. 紫外—可见光谱（UV-Vis）的测量得到,当氩气分量R,即Ar/（Ar+N₂）,为0%时,薄膜的光学带隙为3.90eV,比晶体GaN （c-GaN） 的较大,这主要是由非晶结构中原子无序性造成的;而当R关键词： 非晶氮化镓 溅射 光学带隙 带尾态     

Structural and magnetic properties of NiZn ferrite films with high saturation magnetization deposited by magnetron sputtering

NiZn ferrite films with well-defined spinel crystal structure were in situ fabricated by radio frequency magnetron sputtering at room temperature. The microstructures and static magnetic properties of the films’ dependence on the partial pressure ratio of argon to oxygen gas were investigated. Scanning electron microscope images indicated that all the films consisted of particles nanocrystalline in nature and the sizes increase as the ratio increases in the range of 10-25 nm. A large saturation magnetization (237.2 emu/cm³) and a minimum of coercivity (68 Oe) were obtained when the ferrite film was deposited in the ratio of 4:1. The complex permeability values (μ = μ′−iμ″) of the film were measured at frequency up to 5 GHz. It was shown that the film exhibited a large real part of permeability μ′ of 18 and a very high resonance frequency f_r of 1.2 GHz. The results suggested that the NiZn ferrite film as-deposited in the ratio of 4:1 may be promised as magnetic medium in the application of integrated circuits operating at microwave frequencies.     

Properties of transparent,conducting ZnO films deposited by reactive bias sputtering

Transparent ZnO thin films of resistivity 2×10^?3 Ωcm have been prepared by a reactive bias sputtering technique. Carrier concentration and mobility were determined by Hall probe measurements. Microstructure and grain size were studied using a scanning electron microscope and an X-ray diffractometer. Optical constants were measured for the wavelength range 0.35 to 2.50 μm and infrared reflectivity for the range 2.5 to 20 μm. These optical properties were modelled by the Drude theory of free electrons utilizing measured electrical transport parameters.     

Gadolinia-doped ceria films deposited by RF reactive magnetron sputtering

Gadolinia-doped ceria (GDC) films were prepared by RF reactive magnetron sputtering from a Gd-10 at.% Ce alloy target in reactive O₂/Ar gas mixtures and annealed at 700 °C for 2 h. Material characteristics and chemical compositions of GDC films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Electrical behaviors were measured by AC impedance in the range of 500–700 °C at OCV for air condition. The microstructure of GDC films was found to be an assembly of columnar crystallites with a cubic fluorite structure. The total conductivity of 700 °C-annealed GDC (GDC-1) with the obtained composition of (Ce_0.911Gd_0.089)O_1.938 was higher than that of bulk yttria-stabilized zirconia (YSZ), but smaller than bulk GDC. The governing mechanism of conduction of sputtered-GDC electrolyte films was mainly governed by a grain boundary process, which resulted in a blocking effect and the lower conductivity of thin films than that of bulk GDC samples. Our results suggested that sputtered-GDC films with a comparable conductivity can be used as solid electrolyte layers for a solid oxide fuel cell (SOFC) system as compared to the well-known YSZ.     

Effect of annealing on the magnetic and magnetooptical properties of Ni films

The magnetic and magnetooptical properties of 50-to 200-nm-thick Ni films, both as-deposited and annealed at T_ann = 300, 400, or 500°C, were studied. Volume and near-surface hysteresis loops were measured with a vibrating-sample magnetometer (VSM) and with the use of the transverse Kerr effect (TKE). The annealing temperature was found to exert a strong effect on the magnetic characteristics of the samples under study. It was established, in particular, that the coercivity H _C of Ni films increases and the remanent magnetization decreases with increasing annealing temperature. The observed dependences of the magnetic properties of the films on film thickness and annealing temperature are explained as being due to microstructural characteristics of the samples. It was found that, while TKE spectra obtained in the incident-photon energy region from 1.5 to 6 eV have the same shape for all the Ni films studied, the magnitude of the TKE decreases with increasing T_ann. This experimental observation is accounted for by the decreased saturation magnetization of the annealed films.     

Photocatalytic TiO2 films deposited by rf magnetron sputtering at different oxygen partial pressure

Titanium dioxide (TiO₂) films were deposited onto non-alkali glass substrates by r.f. magnetron sputtering at an [O₂/(Ar + O₂)] flow-rate of 0, 20, 40, 60 and 70%, respectively. The sputtering pressure was 10 mtorr, substrate temperature was around 450 °C after 3 h deposition. The crystalline structure, surface morphology and photocatalytic activity of the TiO₂ films were affected by various [O₂/(O₂ + Ar)] flow-rate ratios. The films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and UV–vis–NIR spectroscopy. X-ray diffraction spectra showed that all the films display anatase (1 0 1) preferred orientation. Photoinduced decomposition of methylene blue (MB) and photoinduced hydrophilicity were enhanced when the [O₂/(Ar + O₂)] flow-rate increased to 60%.