Study of Ge2Sb2Te5 Film for Nonvolatile Memory Medium

The amorphous Ge2Sb2Te5 film with stoichiometric compositions was deposited by co-sputtering of separate Ge, Sb, and Te targets on SiO2/Si (100) wafer in ultrahigh vacuum magnetron sputtering apparatus. The crystallization behavior of amorphous Ge2Sb2Te5 film was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). With an increase of annealing temperature, the amorphous Ge2Sb2Te5 film undergoes a two-step crystallization process that it first crystallizes in face-centered-cubic (fcc) crystal structure and finally fcc structure changes to hexagonal (hex) structure. Activation energy values of 3.636±0.137 and 1.579±0.005 eV correspond to the crystallization and structural transformation processes, respectively. From annealing temperature dependence of the film resistivity, it is determined that the first steep decrease of the resistivity corresponds to crystallization while the second one is primarily caused by structural transformation from     

Emergence of Ag particles and their effects on the mechanical properties of TaN-Ag nanocomposite thin films

TaN-Ag nanocomposite films were deposited by reactive co-sputtering on tool steel substrates. The films were then annealed using RTA (Rapid Thermal Annealing) at 350 °C for 2, 4, 8 min respectively to induce the nucleation and growth of Ag particles in TaN matrix and on film surface. C-AFM (Conductive Atomic force Microscopy) and FESEM (Field-Emission Scanning Electron Microscopy) were applied to examine the Ag nano-particles emerged on the surface of these thin films. A nano-indenter and a pin-on-disk tribometer were used to study the effect of annealing on the films' mechanical properties. The results reveal that annealing by RTA can cause Ag nano-particles to emerge on the TaN surface. Consequently, the mechanical properties of the films will vary depending on annealing conditions, Ag content, and Ag particle emergence.     

Electrical and optical properties of ITO:Ca composite thin films for TEOLED cathode

ITO:Ca composite thin films were deposited on glass substrate by the rf magnetron co-sputtering method with various numbers of Ca chips and oxygen partial pressures. The carrier concentration of the ITO:Ca thin film was 7 × 10²⁰ cm^− 3 when the number of Ca chips was 4 at an oxygen partial pressure of 1.4%. The sheet resistance and optical transmittance of the ITO:Ca thin films were 68.2 Ω/sq. and 87%, respectively. The work function of the ITO:Ca thin films with 8 Ca chips was changed from 4.6 eV to 5.0 eV when the oxygen partial pressure was increased from 0.8% to 2.2%. When the oxygen partial pressure was 1.2%, a low work function of 4.6 eV was obtained for the ITO:Ca thin films.     

Transparent Ga and Zn co-doped In2O3 electrode prepared by co-sputtering of Ga:In2O3 and Zn:In2O3 targets at room temperature

This study examined the characteristics of Ga:In₂O₃ (IGO) co-sputtered Zn:In₂O₃ (IZO) films prepared by dual target direct current (DC) magnetron sputtering at room temperature in a pure Ar atmosphere for transparent electrodes in IGZO-based TFTs. Electrical, optical, structural and surface properties of Ga and Zn co-doped In₂O₃ (IGZO) electrodes were investigated as a function of IGO and IZO target DC power during the co-sputtering process. Unlike semiconducting InGaZnO₄ films, which were widely used as a channel layer in the oxide TFTs, the co-sputtered IGZO films showed a high transmittance (91.84%) and low resistivity (4.1 × 10^− 4 Ω cm) at optimized DC power of the IGO and IZO targets, due to low atomic percent of Ga and Zn elements. Furthermore, the IGO co-sputtered IZO films showed a very smooth and featureless surface and an amorphous structure regardless of the IGO and IZO DC power due to the room temperature sputtering process. This indicates that co-sputtered IGZO films are a promising S/D electrode in the IGZO-based TFTs due to their low resistivity, high transmittance and same elements with channel InGaZnO₄ layer.     

On the elastic modulus and hardness of co-sputtered Zr–Cu–(N) thin metal glass films

This work focuses on the properties of Zr–Cu–(N) deposits obtained by magnetron co-sputtering of Zr and Cu targets in pure argon or in argon nitrogen gas mixtures. Microstructure and mechanical properties (hardness and Young's modulus) were investigated versus deposition parameters. The composition of the Zr–Cu alloy films on the full binary range was accurately controlled by means of the discharge current intensity on both Zr and Cu targets. Deposits were observed to be amorphous single phased in a large range of copper content, the hardness and Young's modulus of the amorphous phase increasing with the latter. A small amount of nitrogen in the gas mixture leads to higher hardness and Young's modulus values.     

共溅射法制备的Pt-C薄膜的微观结构和电化学性能的研究

用共溅射的方法制备了Pt-C薄膜,薄膜由Pt纳米粒子和非晶C组成。电子显微镜和X射线衍射的测试结果显示Pt纳米粒子镶嵌在非晶C之中。高分辨率透射电子显微图像证实了2~3 nm的Pt粒子镶嵌于非晶C层中。Pt和Pt-C薄膜的电化学特性是通过循环伏安法来研究的,电解液为氮气饱和的0.5g/mol的硫酸溶液。与纯Pt薄膜相比,Pt-C薄膜显示了更高的电化学活性面积,这主要是由于非晶C支撑基材的存在降低了Pt纳米颗粒的粒径。     

Characterization of co-sputtered Cu-In alloy precursors for CuInSe2 thin films fabrication by close-spaced selenization

Sputtering technique for Cu–In precursor films fabrication using different Cu and In layer sequences have been widely investigated for CuInSe₂ production. But the CuInSe₂ films fabricated from these precursors using H₂Se or Se vapour selenization mostly exhibited poor microstructural properties. The co-sputtering technique for producing Cu–In alloy films and selenization within a close-spaced graphite box resulting in quality CuInSe₂ films was developed. All films were analysed using SEM, EDX, XRD and four-point probe measurements. Alloy films with a broad range of compositions were fabricated and XRD showed mainly In, CuIn₂ and Cu₁₁In₉ phases which were found to vary in intensities as the composition changes. Different morphological properties were displayed as the alloy composition changes. The selenized CuInSe₂ films exhibited different microstructural properties. Very In-rich films yielded the ODC compound with small crystal sizes whilst slightly In-rich or Cu-rich alloys yielded single phase CuInSe₂ films with dense crystals and sizes of about 5 μm. Film resistivities varied from 10⁻²–10⁸ Ω cm. The films had compositions with Cu/In of 0.40–2.3 and Se/(Cu+In) of 0.74–1.35. All CuInSe₂ films with the exception of very Cu-rich ones contained high amount of Se (>50%).     

Influence of Si-addition on wear and oxidation resistance of TiWSixN thin films

TiWSi_xN films were deposited using a magnetron co-sputtering system on silicon (111), 316L stainless steel, and M2 high-speed steel substrates. The silicon target current density was varied from 0 mA/cm² to 4.32 mA/cm² in order to modify the Si content in the films. The microstructure and chemical composition were determined by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The surface of the films was explored via scanning electron microscopy (SEM) and atomic force microscopy (AFM). Mechanical, tribological, and thermal properties were investigated by means of the nanoindentation, ball-on-disc, and cyclic oxidation tests, respectively. Our results indicated that as the silicon target current density was increased, the microstructure changed from crystalline to amorphous, and the hardness and elastic modulus improved from initial values of 7.5 ± 0.3 GPa and 181 ± 8 GPa to 15 ± 1 GPa and 229 ± 9 GPa, respectively. Furthermore, films deposited at high silicon target current exhibited better resistance to thermal oxidation. The failure mechanism of the WTiSi_xN thin films under cyclic oxidation was attributed to the microstructure of the films, WO₃ sublimation, and the thermal coefficient mismatch between the film and the substrate.     

Photocatalytic and antibacterial properties of TaON-Ag nanocomposite thin films

TaON-Ag nanocomposite thin films with Ag nano-particles embedded in TaON were prepared by reactive co-sputtering of Ta and Ag in the plasma of (O₂ + N₂)/Ar. The deposition temperature was either at room temperature or 300 °C. These films were characterized mainly by UV-Vis photometry and scanning electron microscopy. It is found that Ag doping into the TaON films leads to several beneficial changes on film properties. It would reduce the optical band gap and, therefore, enhance the films' photocatalytic behavior. It is also found that Ag nano-particles may emerge on the surface of TaON with or without RTA. This could be much meaningful since Ag particles' appearance is closely related to the antibacterial property of TaON-Ag films. The results show that TaON-Ag films deposited at 300 °C have an outstanding antibacterial behavior with the illumination of visible light due to the synergistic effects of Ag and photocatalytic behavior of TaON.     

Microstructural analysis and mechanical properties of TaN-Ag nanocomposite thin films

TaN-Ag nanocomposite thin films with Ag nanoparticles dispersed in TaN matrix and surface were prepared by reactive co-sputtering of Ta and Ag in a plasma of N₂ and Ar. The films were then annealed using RTA (Rapid Thermal Annealing) at various annealing times and annealing temperatures to induce the nucleation and growth of Ag particles in the TaN matrix and on the film surface. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) were applied to examine the microstructure and surface morphology of TaN-Ag thin films. It is found that Ag tends to precipitate on the columnar boundaries when Ag concentration is low. In this case, the hardness as well as the resistance-to-crack can be enhanced. When Ag concentration is high, the TaN columnar structure is disrupted which can reduce the hardness and resistance-to-crack. Overall, the results reveal that the hardness and crack resistance of these films can be controlled by varying Ag contents and annealing conditions.