Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films

Alumina (Al₂O₃) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al₂O₃-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed.     

磁控溅射CrNx薄膜的制备与力学性能

采用反应磁控溅射法在不同的氮分压下制备了一系列CrNx薄膜,并利用EDS和XRD表征了薄膜的成分和相组成,采用力学探针测量了薄膜的硬度和弹性模量。研究了氮分压对薄膜成分,相组成和力学性能的影响。结果表明,随氮分压的升高,薄膜的沉积速率明显降低,薄膜中的氮含量量增加,相应地,相组成从Cr Cr2N过渡到单相Cr2N,再逐步经Cr2N CrN过渡到单相CrN,并在Cr:N原子比为1：2和1：1时,薄膜的硬度出现极值（HV27．1GPa和HV26.8GPa),而薄膜的弹性模量则在Cr2N时呈现350GPa的最高值。     

Impact of substrate temperature on the microstructure, electrical and optical properties of sputtered nanoparticle V2O5 thin films

Applying reactive direct current (DC) magnetron sputtering method, nanoparticle vanadium pentoxide thin films were deposited onto glass slides and KBr substrates at different substrate temperatures. The films were characterized by X-ray photoelectron spectroscopy and atomic force microscope. Infrared spectra were recorded with a Fourier transform infrared spectrophotometer. It was found that, excepting the compositions, the film growth and vanadium oxygen bonds were strongly affected by the substrate temperature. Electrical measurements indicated that the square resistances of films showed an exponential decrease from 46 MΩ/□ to 33 kΩ/□ with substrate temperature increasing from 433 K to 593 K, and that the square resistance-temperature curves of films exhibited typical semiconducting behavior. Optical investigations were carried out in the near infrared and ultraviolet-visible range. Transmittance varied from about 95 to 55% in near-infrared range when the substrate temperature was elevated. In ultraviolet-visible range, optical band gaps and refractive indexes of films were deduced according to the transmission and reflection spectra.     

R.F. magnetron sputtered tungsten carbide thin films

Thin films of tungsten carbide have been deposited on stainless steel substrates held at 500°C by r.f. reactive magnetron sputtering in two different modes of introducing argon and acetylene gases called normal and high rate mode. A single phase fcc-WC is formed in the normal mode whereas a mixture of A-15-W₃C, hexagonal-WC and graphitic- and diamond-carbon is found in the high rate mode. A microhardness value as high as 3200 kgf/mm² (as compared to the bulk value of 1800 kgf/mm²) is obtained in the film deposited by normal mode.     

Morphological study of magnetron sputtered Ti thin films on silicon substrate

Titanium films on Si(1 0 0) substrate were deposited by DC-magnetron sputtering. The effect of substrate temperature on the microstructural morphologies of the films was characterized by using field emission-based scanning electron microscopy/electron back scattered difffraction (FE-SEM/EBSD) and atomic force microscopy (AFM). X-ray diffraction was used to characterize the phases and crystallite size of the Ti films and it was observed that according to the first figure of this article: (0 0 2) orientation increases from 200 °C and it changes into (1 0 1) orientation from 300 °C. The SEM analysis of the Ti films, deposited in Ar atmosphere, showed two- and three-dimensional hexagonal structure of the grains at the substrate temperature of 200 °C and >200 °C, respectively. The increase in grain size of Ti films with the substrate temperature was confirmed by EBSD and AFM characterization. The average surface roughness of the Ti films has increased with increase in substrate temperature as evident from the AFM study.     

In-situ deposition of superconducting YBCO thin films by magnetron sputtering from powder target

We have used stoichiometric Y₁Ba₂Cu₃O_7–x powder as magnetron sputtering target to deposit high-quality high-T _c superconducting thin films on MgO, SrTiO₃, and ZrO₂ substrates. The zero-resistance temperatures are 86–88 K, and the 77 K zero-field critical current density is 8 × 10⁵ A/cm². The films are highlyc-axis oriented. Films deposited on 10 × 10 × 1 mm³ ZrO₂ substrates have surface resistances below 25 m at 77 K and 94 GHz. Using powder targets instead of bulk targets has the following advantages: simple and low-cost target preparation, simple target replacement, and versatility for large-area deposition.     

射频磁控溅射制备硼碳氮薄膜

采用射频磁控溅射技术,用六角氮化硼和石墨为溅射靶,以氩气(Ar)和氮气(N2)为工作气体,在Si (100)衬底上制备出硼碳氮薄膜.通过X射线衍射(XRD)、傅里叶红外吸收光谱(FTIR)和X射线光电子能谱(XPS)等分析手段对样品结构、组分进行了分析.结果表明,样品的组成原子之间实现了原子级化合,且薄膜为乱层石墨结构.样品中B、C、N的原子比近似为1:1:1.     

HfO2薄膜的制备与光学性能

采用射频磁控反应溅射法，以高纯热压HfO2陶瓷为靶材，在Si衬底上成功制备出HfO2薄膜。系统研究了工艺参数对薄膜沉积速率的影响规律，并对薄膜的光学性能进行了研究。结果表明，射频功率对薄膜沉积速率的影响最为明显，O2／Ar流量比和衬底温度对沉积速率的作用不明显，所制备薄膜的折射率较高在近红外波段趋于1．95，在500-1650nm波段范围内薄膜几乎无吸收，透过率较高。     

Ar气氛下直流磁控溅射ITO薄膜的结构和性能

采用直流磁控溅射法在低温、100%Ar的无氧气氛中制备了光电性能优良的铟锡氧化物(ITO,In2O3:SnO2=90:10,质量百分比)薄膜,详细探讨了溅射时改变氩气压强对ITO薄膜结构以及光电性能的影响.结果表明:溅射时氩气压强越小,ITO薄膜的体心立方晶型越完整,导电性越好,但对可见光透过性的影响不大.当氩气压强为0.3Pa时,溅射薄膜性能最佳,其光透过率可达92.9%,电导率为8.9×10-4Ω·cm.     

Al-Mg-B thin films prepared by magnetron sputtering

Hard, nanocomposite aluminum magnesium boride thin films were prepared on Si (100) substrates with a three target magnetron sputtering system. The films were characterized by X-ray diffraction, atomic force microscope, electron micro-probe, Fourier transform infrared spectroscopy and nanoindentation. The results show that the maximum hardness of the as-deposited films is about 30.7 GPa and these films are all X-ray amorphous with smooth surfaces. The influences of substrate temperature and boron sputtering power on the quality of the films are discussed. From the results of this work, magnetron sputtering is a promising method to deposit Al-Mg-B thin films.     

On the structural and electrical characteristics of zinc oxide thin films

ZnO thin films with thickness d = 100 nm were deposited by radio frequency magnetron sputtering onto glass substrate from different targets. The structural analyses of the films indicate they are polycrystalline and have a wurtzite (hexagonal) structure. Crystallites are preferentially oriented with (002) plane parallel to the substrate surface and the samples have low values for surface roughness, between 1.7 nm and 2.7 nm. The mechanism of electrical conduction in the studied films is strongly influenced by this polycrystalline structure and we used Van der Pauw method to analyze these properties. Electrical studies indicate that the ZnO thin films are n-type. For the cooling process, thermal activation energy of electrical conduction of the samples can vary from 1.22 eV to 1.07 eV (for the ZnO layer obtained from for metallic Zn target) and from 0.90 eV to 0.63 eV (for the ZnO layer obtained from ZnO target), respectively. The influence of deposition arrangement and oxidation conditions on the structural and electrical properties of the ZnO films was investigated in detail.     

Structural properties of RF-magnetron sputtered Cu2O thin films

Cuprous oxide thin films were produced on soda-lime glass substrates using reactive RF-magnetron sputtering. The influence of deposition parameters and temperature on composition and structural properties of the single layers was extensively studied using X-ray diffraction. The control over microstructure and residual stresses is possible by changing reactive gas pressure and deposition temperature. Fiber textured Cu2O films showing a [100] preferred orientation and a fraction of untextured domains can be obtained: suitable modeling taking this microstructure into account shows the presence of a strong compressive stress decreasing with the temperature. Highly reproducible films can be obtained, whose microstructure is preserved when sputtering on tungsten and zinc oxide substrates.     

Preparation of ITO thin films applied in nanocrystalline silicon solar cells

ITO thin films were prepared by changing the experimental parameters including gas flow ratio, sputtering pressure and sputtering time in DC magnetron sputtering equipment. The stable experimental parameters of Ar flow at 70 sccm, O₂ flow at 2.5 sccm ∼ 3.0 sccm, sputtering pressure around 0.5 Pa, and sputtering time of 80 s were obtained. Under these parameters, we had achieved the ITO thin films with low resistivity (<4 × 10⁻⁴ Ω ? cm) and high average transmissivity (95.48%, 350 nm ∼ 1100 nm). These ITO thin films were applied in nanocrystalline silicon solar cells as top transparent conductive layer. The solar cell test result showed that the open circuit voltage (Voc) was up to 534.9 mV and the short circuit current density (Jsc) was 21.56 mA/cm².     

HTSC thin film growth by inverted cylindrical magnetron sputtering

Inverted cylindrical magnetron sputtering (ICM) is a reliable and reproducible method for the production of HTSC thin films. This allows systematic studies of film growth as a function of various deposition parameters, including film thickness, substrate material, or buffer layers. After describing in some detail the special demands on sputtering devices for HTSC thin film growth, we report the growth conditions and growth quality of 1–2–3 films of different orientation on substrates such as SrTiO₃ and MgO. Furthermore, we report on the growth of buffer layers of YSZ onR-plane sapphire. Epitaxial GdBa₂Cu₃O₇ films grown on these buffer layers showed critical current densities of 3×10⁶ A/cm² at 77 K and a zero resistance transition temperature of 92.5 K.     

Preparation and characterization of sputtered Cu films containing insoluble Nb

Copper films containing various amounts of insoluble Nb (up to 24.7 at.%) were prepared by r.f. magnetron sputtering. The crystallography and microstructure of the films were investigated for as-deposited and annealed Cu(Nb) thin films. Cu(Nb) thin films are found to consist of non-equilibrium supersaturated solid solution of Nb in Cu with a nanocrystalline microstructure. X-ray diffraction and scanning electron microscope analyses revealed a reduction in the grain sizes of the films with increasing Nb content in the films leading to a grain refinement. The electrical resistivity of as-deposited and annealed Cu(Nb) thin films is found to be low for an Nb content 2.7 at.%. Significant drops in the resistivity were observed for the high Nb contents after annealing at 530 °C which may be due to grain growth and formation of Nb-bearing phase in the film. Microhardness of the films was found to increase with the Nb concentration due to the combined effects of grain refinement and the solute strengthening of Nb.     

Effect of process parameters and post deposition annealing on the optical, structural and microwave dielectric properties of RF magnetron sputtered (Ba0.5,Sr0.5)TiO3 thin films

Thin films of (Ba_0.5,Sr_0.5)TiO₃ (BST5) in the thickness range 400-800 nm have been deposited by RF magnetron sputtering on to quartz substrates at ambient temperature. All the properties investigated, i.e. structure, microstructure, optical and microwave dielectric, show a critical dependence on the processing and post processing parameters. The surface morphology as studied by atomic force microscopy reveals ultra fine grains in the case of as deposited films and coarse grain morphology on annealing. The as-deposited films are X-ray amorphous and exhibit refractive index in the range 1.9-2.04 with an optical absorption edge value between 3.8 and 4.2 eV and a maximum dielectric constant of 35 at 12 GHz. The dispersion in refractive index fits into the single effective oscillator model while the variation in the optical parameters with oxygen percentage in the sputtering gas can be explained on the basis of packing fraction changes. On annealing the films at 900 °C they crystallize in to the perovskite structure accompanied by a decrease in optical band gap, increase in refractive index and increase in the microwave dielectric constant. At 12 GHz the highest dielectric constant achieved in the annealed films is 175. It is demonstrated that with increasing oxygen-mixing percentage in the sputtering gas, the microwave dielectric loss decreases while the dielectric constant increases.     

Modeling of metastable phase formation diagrams for sputtered thin films

A method to model the metastable phase formation in the Cu–W system based on the critical surface diffusion distance has been developed. The driver for the formation of a second phase is the critical diffusion distance which is dependent on the solubility of W in Cu and on the solubility of Cu in W. Based on comparative theoretical and experimental data, we can describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation. Metastable phase formation diagrams for Cu–W and Cu–V thin films are predicted and validated by combinatorial magnetron sputtering experiments. The correlative experimental and theoretical research strategy adopted here enables us to efficiently describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation during magnetron sputtering.     

氮流量对TaN薄膜微结构及性能的影响

采用反应直流磁控溅射法在Al2O3陶瓷基片上制备TaN薄膜,研究了氮流量(N2/(N2+Ar))对TaN薄膜微结构及性能的影响。结果表明,随氮流量的增大,TaN薄膜的氮含量、电阻率、方阻以及TCR的绝对值逐渐增大,而沉积速率逐渐降低。当N2流量较低(2%～4%)时,TaN薄膜中主要含有电阻率和TCR绝对值较低的六方Ta2N相(hcp),薄膜的电阻率在344μΩ.cm到412μΩ.cm范围内,薄膜的TCR绝对值约为几十ppm/℃。当氮气流量较高(5%～6%)时,薄膜中Ta2N相消失,薄膜中主要含有TCR绝对值较大的体心四方结构(bct)的TaN和四方结构(bct)的Ta3N5相,薄膜的电阻率在940μΩ.cm到1030μΩ.cm范围内,薄膜的TCR绝对值约为几百ppm/℃。     

陶瓷靶射频磁控溅射TiO2薄膜的制备和光催化特性

Transparent titania thin films were prepared on glass substrates by radio frequency magnetron sputtering from TiO2 ceramic target. The structure and morphology of those films with different sputtering power and substrate temperature has been measured with X-ray diffractometer (XRD) and atomic force microscope (AFM). It was found that the films were anatase and a mix of anatase-rutile with different condition. The transmission of the films has been studied by using UV-VIS-NIR spectrometer. It shows absorption edge has a little red shift with the increase of sputtering power and substrate temperature. The photocatalytic activity of the films was tested on the degradation of Rhodamine B solution. T.he highest degradation efficiency in our experiment was obtained in the film deposited at 550℃ and 130W.     

退火温度对TiO2薄膜结构与光学性能的影响

研究退火温度对薄膜相结构、表面化学组成、形貌及光学性能的影响.采用射频磁控溅射法在单晶硅片和石英玻璃片上负载TiO2薄膜,通过X射线衍射(XRD)、原子力显微镜(AFM)、X光电子能谱(XPS)和紫外可见光谱(UV-vis)对其进行表征.结果表明,常温制备400℃以下退火的TiO2薄膜为无定形结构,400℃以上退火的TiO2薄膜出现锐钛矿相,600℃以上退火的TiO2薄膜开始出现金红石相,退火温度在1000℃以上时样品已经完全转变为金红石相;高温退火薄膜的组成为TiOx;随着退火温度的升高,薄膜透射率下降,折射率和消光系数有所增加.