Analysis of precursors for crystal growth of YBaCuO thin films in magnetron sputtering deposition

We correlated the crystallinity of YBaCuO films prepared by magnetron sputtering deposition using Ar/O₂ mixture gas with the atomic and molecular composition in the gas phase. YBaCuO films were deposited on MgO substrates at 670 °C. Two-dimensional distributions of Y, Ba, Cu, YO, BaO, and CuO densities and one-dimensional distribution of O density were measured by laser-induced fluorescence spectroscopy. The Y and Ba densities decreased significantly with the increase of the O₂ partial pressure, and they were below the detection limit at an O₂ flow ratio of 10% and a total gas pressure of 53 Pa. The decrease in the Y and Ba densities was compensated by an increase in the YO and BaO densities. The decrease in the Cu density with the increase of the O₂ partial pressure was less significant, while the CuO density was below the detection limit at all the discharge conditions. The O density was evaluated to be 10¹²-10¹³ cm^− 3, which was much higher than the Cu density. On the other hand, YBaCuO films with high crystallinity were obtained at total gas pressures of 53-80 Pa and O₂ flow ratios of 50-70%. Therefore, it is concluded that the precursors for the deposition of YBaCuO films with high crystallinity are Cu, YO, BaO, and O.     

Investigation on Mn doped ZnO thin films grown by RF magnetron sputtering

In this paper, we have investigated the Zn_1 − x Mn_xO (x = 0.05, 0.10 and 0.15) thin films grown by RF magnetron sputtering. The grown films on sapphire [Al₂O₃(0001)] substrates have been characterized using X-ray Diffraction (XRD), Photoluminescence (PL) and Vibrating Sample Magnetometer (VSM) in order to investigate the structural, optical and magnetic properties of the films respectively. It is observed from XRD that all the films are single crystalline with (002) preferential orientation along c-axis. PL spectra reveal that the addition of Mn marginally shifts the Near Band Edge (NBE) position towards the higher energy side. The magnetic measurements of the films using VSM clearly indicate the ferromagnetic nature.     

Growth and properties of ZnS thin films by sulfidation of sputter deposited Zn

ZnS thin films with the hexagonal structure have been produced by sulfurizing sputter deposited Zn in sulfur vapor for 1 h. These films have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), synchrotron radiation photoelectron spectroscopy (SR-PES), Auger electron spectroscopy (AES) and UV-VIS transmission spectra. It is found that at the sulfidation temperature (T_S) of 400 °C a little and partial Zn can be transformed to ZnS. At T_S = 500 °C, the total conversion of Zn in sulfur vapor can take place and form ZnS with a c-axis preferred orientation. The Zn-to-ZnS conversion is kinetically a reactive diffusion process. Also the ZnS thin film has much greater size of grains than the as-deposited Zn film, due to ZnS recrystallization and growth in sulfur vapor. Residual sulfur existing on the surface of ZnS grains leads to the poor optical transparency and great broadening of absorbing edge in the optical transmittance. However, ZnS thin film prepared by gradient sulfidation exhibits the improved optical transmittance, with a band-gap energy of 3.64 eV.     

Fluorine-doped ZnO transparent conducting thin films prepared by radio frequency magnetron sputtering

Fluorine-doped ZnO transparent conducting thin films were prepared by radio frequency magnetron sputtering at 150 °C on glass substrate. Thermal annealing in vacuum was used to improve the optical and electrical properties of the films. X-ray patterns indicated that (002) preferential growth was observed. The grain size of F-doped ZnO thin films calculated from the full-width at half-maximum of the (002) diffraction lines is in the range of 18-24 nm. The average transmittance in visible region is over 90% for all specimens. The specimen annealed at 400 °C has the lowest resistivity of 1.86 × 10^− 3 Ω cm, the highest mobility of 8.9 cm² V^− 1 s^− 1, the highest carrier concentration of 3.78 × 10²⁰ cm^− 3, and the highest energy band gap of 3.40 eV. The resistivity of F-doped ZnO thin films increases gradually to 4.58 × 10^− 3 Ω cm after annealed at 400 °C for 4 h. The variation of the resistivity is slight.     

Dielectric oxynitride LaTiOxNy thin films deposited by reactive radio-frequency sputtering

LaTiO_xN_y thin films have been deposited by RF sputtering on (001) Nb-doped SrTiO₃ and (001) MgO single-crystalline substrates at high temperature (T_S = 800 °C) under different nitrogen ratios in the plasma (vol.% N₂ = 0, 25, 71). The band gaps ranged from E_g = 3.30 eV for the epitaxial transparent film containing no nitrogen to E_g = 2.65 eV for the textured coloured film containing a moderate amount of nitrogen. Dielectric characterization in the frequency range [100 Hz-1 MHz], using a metal-insulator-metal structure, has shown a stable permittivity and loss tangent of the epitaxial low-nitrided LaTiO_xN_y film with values of ε′ = 135 and tanδ = 1.2 10^− 2 at 100 kHz (RT).     

Influence of substrate temperature on N-doped ZnO films deposited by RF magnetron sputtering

Nitrogen-doped ZnO films were deposited by RF magnetron sputtering in 75% of N₂ / (Ar + N₂) gas atmosphere. The influence of substrate temperature ranging from room temperature (RT) to 300 °C was analyzed by X-ray diffractometry (XRD), spectrophotometry, X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS) and Hall measurements setup. The XRD studies confirmed the hexagonal ZnO structure and showed that the crystallinity of these films increased with increasing substrate temperature (T_s). The optical studies indicate the average visible transmittance in the wavelength ranging 500-800 nm increases with increasing T_s. A minimum transmittance (9.84%) obtained for the films deposited at RT increased with increasing T_s to a maximum of 88.59% at 300 °C (500-800 nm). Furthermore, it was understood that the band gap widens with increasing T_s from 1.99 eV (RT) to 3.30 eV (250 °C). Compositional analyses (XPS and SIMS) confirmed the nitrogen (N) incorporation into the ZnO films and its decreasing concentration with increasing T_s. The negative sign of Hall coefficients confirmed the n-type conducting.     

Influence of sputtering parameters on crystalline structure of ZnO thin films

The relations between the sputtering parameters and the crystalline microstructure of ZnO thin films are presented. The energetic bombardment of substrate by neutral atoms, ions and electrons during sputtering is characterized by total energy flux density which affects the film. This parameter can be estimated by RF power, substrate bias voltage and concentration of reactive gases. Substrate temperature and total energy flux density are the major parameters which have a significant influence on ZnO thin film crystalline structure.     

Magnetron sputtering of Zr-Si-C thin films

The phase composition and chemical bonding of ZrC and ZrSiC films deposited by magnetron sputtering has been studied. The results show that the binary Zr-C films at higher carbon contents form nanocrystallites of ZrC in an amorphous carbon matrix. The addition of Si induces a complete amorphization of the films above a critical concentration of about 15 at.%. X-ray diffraction and transmission electron microscopy confirm that the amorphous films contain no nanocrystallites and therefore can be described as truly amorphous carbides. The amorphous films are thermally stable but start to crystallize above 500 °C. Analysis of the chemical bonding with X-ray photoelectron spectroscopy suggests that the amorphous films exhibit a mixture of different chemical bonds such as ZrC, ZrSi and SiC and that the electrical and mechanical properties are dependent on the distribution of these bonds. For higher carbon contents, strong SiC bonds are formed in the amorphous Zr-Si-C films making them harder than the corresponding binary Zr-C films.     

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.     

Effect of oxygen partial pressure on the structural and optical properties of sputter deposited ZnO nanocrystalline thin films

We report the influence of deposition parameters such as oxygen partial pressure and overall sputtering pressure on the structural and optical properties of the as-grown ZnO nanocrystalline thin films. The films were prepared by dc magnetron sputtering using Zn metal target under two different argon and oxygen ratios at various sputtering pressures. Microstructure of the films was investigated using X-ray diffraction and scanning electron microscopy. Optical properties of the films were examined using UV-Visible spectrophotometer. The results show that the films deposited at low oxygen partial pressure (10%) contain mixed phase (Zn and ZnO) and are randomly oriented while the films deposited at higher oxygen partial pressure (30%) are single phase (ZnO) and highly oriented along the c-axis. We found that the oxygen partial pressure and the sputtering pressure are complementary to each other. The optical band gap calculated from Tauc's relation and the particle size calculation were in agreement with each other.     

溅射功率对磁控溅射ZnO∶Al(ZAO)薄膜性能的影响

采用射频磁控溅射工艺,以高密度氧化锌铝陶瓷靶为靶材,衬底温度控制在室温,在玻璃基底上制备了透明导电Zn O∶Al(ZAO)薄膜。利用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外-可见光谱仪和范德堡法,系统研究了不同溅射功率对薄膜的结构、形貌及光电特性的影响。结果表明,不同溅射功率对薄膜的光透射率影响不大,而对薄膜结晶和电学性能影响较大。XRD表明薄膜为良好的c轴择优取向;可见光区(400~600 nm)平均透过率达到85%以上;在120W下沉积的薄膜电学性能达到了最佳。     

Improvement in thermal stability of B-C-N thin films fabricated by magnetron sputtering using graphite and BN co-target

Thermal stability of amorphous boron-carbon-nitride (B-C-N) films fabricated by magnetron sputtering using a graphite and BN co-target was studied by X-ray photoelectron spectroscopy, infrared absorption spectroscopy, Raman spectroscopy and scanning electron microscopy. The boron-rich B-C-N films showed the higher thermal stability. These results suggest that an incorporation of B atoms into the amorphous CN networks improves the thermal stability. This improvement can be explained in terms of the creation of boron-nitrogen bonds and/or boron-carbon bonds.     

Mechanical and deformation behaviour of titanium diboride thin films deposited by magnetron sputtering

Nanoindentation studies have been carried out for TiB₂ films deposited on Si, glass and steel by sputtering for studying the influence of the substrates. It was observed that the modulus of the film was influenced by the substrates from 30 nm onwards. Plastic energy analysis has shown that as load increases more energy is absorbed by the substrate. Quantitative indentation depth limits for obtaining film only hardness, using a combination of log-log plot of load vs displacement and load vs (displacement)² functions, have shown the dependence on the threshold load for crack formation. Comparison of the hardness data with composite hardness models has been performed. Fracture toughness of the coatings was also evaluated using two methods which resulted in comparable results.     

Material properties of Au-Pd thin alloy films

Thin films of Au-Pd of varying composition were formed by electron beam physical vapor deposition. They were characterized and their application as optical hydrogen sensors was studied. In addition, parameters of sensing performance such as Pd deficiency during deposition, grain size, compositional homogeneity, and the appearance of a natural buffer layer, were examined. Following deposition, Au-Pd films exhibited high atomic intermixing, and a PdO_x buffer layer formed spontaneously. This layer makes it possible to increase film thickness, which improves the intensity of the detecting signal. Accordingly, the suggested deposition method may optimize recent efforts to use Au20 wt.%-Pd thin alloy film in optical hydrogen sensors.     

Structural and superconducting properties of Nb-Ti alloy thin films

The structural instability in Ti rich compositions of Nb-Ti alloy system, which leads to various anomalies in the normal and superconducting state properties, has been extensively studied in bulk samples in the past. In this paper we report the formation of thin films of several compositions in the Ti rich region of this alloy system by RF magnetron sputtering and investigation of their electrical properties. Compositional analysis of two representative films was carried out by the RBS technique and the compositions agreed to within 2% of the targeted values. The anomalous variations in the electrical properties characteristic of the bulk, which can be ascribed to the structural instability related to the formation of athermal ω-phase, are also observed in thin films.     

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.     

Substrate temperature effects on the growth and properties of γ-MnS thin films grown by rf sputtering

The growth of manganese(II) sulfide films by radiofrequency sputtering are shown for the first time. Polycrystalline, nearly stoichiometric films of the metastable hexagonal γ-MnS phase were obtained when the substrate temperature was approximately 26°C. For higher substrate temperatures, 120 and 180°C, the films were amorphous and sulfur deficient. The sulfur loss is substrate-temperature dependant. This behavior is discussed in terms of the dissociation of the MnS molecules during the sputtering process and the phase diagram of sulfur. An analysis of the optical transmission spectrum of the γ-MnS films allowed us to estimate their index of refraction in the non-absorbing region of the spectrum and the electronic band gap in the high absorbance region, obtaining an E_g value of 3.47±0.01 eV at room temperature.     

Properties of Al heavy-doped ZnO thin films by RF magnetron sputtering

Al-doped ZnO films were deposited by RF magnetron sputtering. From the X-ray diffraction and scanning electron spectrometer studies, wurtzite structure with (0 0 2) orientation ZnO thin films were obtained at Al concentration below 15 atomic percent (at.%). As the Al concentration above 15 at.%, the thin films did not fully crystallize. Two new emission peaks occurred at 351 nm and 313 nm when the Al doping above 15 at.% from the photoluminescence spectrum, and the peaks shift towards the shorter wavelengths with increasing the Al concentration. X-ray photonic spectra of O 1s conformed the amount of oxygen captured by Al³⁺ increasing as the Al³⁺ concentration increasing due to the dominant Al³⁺ possess high charge in competition with Zn²⁺ in the matrix of ZnO.     

Investigation of thin solid ZnO films prepared by sputtering

Zinc oxide (ZnO) thin films have attracted great attention in recent years due to their unique piezoelectric and piezooptic properties, making them suitable for various microelectronics and optoelectronics applications, such as surface acoustic wave devices, optical fibers, solar cells etc. ZnO is a semiconductor with a band gap of 3.3 eV and a large exciton binding energy of 60 meV. Undoped ZnO exhibits intrinsic n-type conductivity and it enables achieving high electron concentration. However, it may be doped to obtain low resistivity p-type thin films. Among group V of the periodic table, nitrogen is used as a popular p-type dopant due to its small atomic size. However, it is difficult to achieve p-type conduction in ZnO films due to the low solubility of nitrogen and its high intensity in self compensating process upon doping.Sputtering techniques enable us to form dense and homogeneous films due to the relatively high energy of the sputtered atoms. Thus we can grow high quality ZnO films with c-axis orientation, low growth temperature, high deposition rate, large area deposition, and availability in various growths ambient. In this work, the zinc oxide films were prepared using various DC sputtering methods in an atmosphere of pure argon and an atmosphere of mixed argon with nitrogen. Optical and electrical properties of the films were investigated.     

Growth of lithium tantalate thin films by radio-frequency magnetron sputtering with lithium enriched target

LiTaO₃ thin films were deposited by radio-frequency magnetron sputtering with a Li enriched target composed of Li₂O₂/Ta₂O₅ (55:45 at.%). Morphology, crystallinity, dielectric and pyrolectric properties of thin films of LiTaO₃ are studied according to the temperature of deposition and the nature of the back electrode (Ru/RuO₂ and RuO₂). In order to develop thermal microsensors containing pyrolectric thin layers deposited on membranes of SiN_x ensuring the thermal isolation of the device, the final aim is to improve the pyroelectric coefficient for infrared pyroelectric detectors applications. The best pyroelectric coefficient of LiTaO₃ thin films (400 nm), obtained for a growth temperature of 620 °C and a pressure of 0.67 Pa, is equal to 40 µC/m² K.