Study of Cu emergence on the surface of TaN-Cu nanocomposite thin films and its effects on tribological property

TaN-Cu nanocomposite films, were deposited by reactive co-sputtering on Si and tool steel substrates. The films were then annealed using RTA (Rapid Thermal Annealing) at 400 °C for 2, 4, 8 min respectively to induce the nucleation and growth of Cu particles in the TaN matrix and on the film surface. SSPM (Scanning Surface Potential Microscopy) and SEM (Scanning Electron Microscopy) were applied to examine the Cu nano-particles that emerged on the surface of TaN-Cu thin films. Pin-on-Disk tribometer was used to study the effect of annealing on the films' tribological properties. The results reveal that annealing by RTA can cause Cu nano-particles to emerge on the TaN surface. Consequently, hardness and friction coefficients will change depending on annealing conditions, Cu content, and/or Cu particle emergence.     

Effect of selenization pressure on CuInSe2 thin films selenized using co-sputtered Cu-In precursors

CuInSe₂ thin films were formed from the selenization of co-sputtered Cu–In alloy layers. These layers consisted of only two phases, CuIn₂ and Cu₁₁In₉, over broad Cu–In composition ratio. The concentration of Cu₁₁In₉ phase increased by varying the composition from In-rich to Cu-rich. The composition of co-sputtered Cu–In alloy layers was linearly dependent on the sputtering power of Cu and In targets. The metallic layers were selenized either at a low pressure of 10 mTorr or at 1 atm Ar. A small number of Cu–Se and In–Se compounds were observed during the early stage of selenization and single-phase CuInSe₂ was more easily formed in vacuum than at 1 atm Ar. Therefore, CuInSe₂ films selenized in vacuum showed smoother surface and denser microstructure than those selenized at 1 atm. The results showed that CuInSe₂ films selenized in vacuum had good properties suitable for a solar cell.     

Fabrication and characterization of highly luminescent Er3+:Al2O3 thin films with optimized growth parameters

Erbium doped amorphous alumina thin films were fabricated using Co-sputtering technique in various depositions runs with varying parameters for optimizing the deposition parameters to obtain the films with best optical performance. The main subject of investigation includes the effects of change in various deposition parameters such as substrate heating, radio frequency (RF) power and oxygen pressure inside the chamber while deposition. High quality as-deposited films with various Er concentrations and low carbon content have been confirmed by XPS. Substrate heating ∼500 °C was found to be very effective in getting highly dense films with high refractive index of 1.70 at 1530–1570 nm emission band. The Er³⁺-doped films showed very intense near-infrared luminescence peak at 1550 nm even without any post-deposition annealing treatment.     

多靶直流磁控共溅射系统的研制

本文报道了多靶直流磁控共溅射系统的设计及性能，三个直流磁控溅射枪呈１２０°空间角分布于真空罩上，并聚焦于基板中心，靶的有效直径为φ５０ｍｍ，靶平面的法线与基板的法线成６０°夹角，基板可绕中心轴旋转。该系统中生长出φ７０ｍｍ范围内膜厚均匀的大面积薄膜，特别适合于制备大面积、多组元金属氧化物薄膜及合金薄膜。     

Formation of the distributed NiSiGe nanocrystals nonvolatile memory formed by rapidly annealing in N2 and O2 ambient

In this work, electrical characteristics of the Ge-incorporated Nickel silicide (NiSiGe) nanocrystals memory device formed by the rapidly thermal annealing in N₂ and O₂ ambient have been studied. The trapping layer was deposited by co-sputtering the NiSi₂ and Ge, simultaneously. Transmission electron microscope results indicate that the NiSiGe nanocrystals were formed obviously in both the samples. The memory devices show obvious charge-storage ability under capacitance-voltage measurement. However, it is found that the NiSiGe nanocrystals device formed by annealing in N₂ ambient has smaller memory window and better retention characteristics than in O₂ ambient. Then, related material analyses were used to confirm that the oxidized Ge elements affect the charge-storage sites and the electrical performance of the NCs memory.     

Sputter deposition and computational study of M-TiO2 (M = Nb, Ta) transparent conducting oxide films

Titanium dioxide (TiO₂) of the anatase phase has recently attracted much attention as a novel transparent conducting oxide (TCO) due to its rich availability, high refractive index with low absorption in the solar spectrum. While it has been found that Nb is a dopant to obtain low resistivity (~ 10^− 4 Ωcm), other metals such as Ta, W etc., are also considered as potential effective dopants. In this paper, we carried out a parallel study on Nb- and Ta-doped TiO₂ anatase films both theoretically by first principles calculation and experimentally by sputtering deposition and optical/electrical characterizations. The Nb-TiO₂ films deposited on glass by co-sputtering at room temperature were amorphous, and the films crystallized into an anatase structure after vacuum-annealing, with the measured resistivity values comparative to the reported. The Ta-TiO₂ films were deposited similarly, and the structure and properties were compared with the Nb-doped ones. Results showed that better performance was found in Nb-TiO₂ films than that in Ta-TiO₂ films. Theoretical calculations indicate that the larger lattice distortion by substitution of Ta for Ti is the dominating factor to suppress crystal growth and weaken the ability of electron mobility.     

Effects of Ag contents and deposition temperatures on the electrical and optical behaviors of Ag-doped Cu2O thin films

Cu₂O-Ag thin films were co-deposited by reactive sputtering on glass substrates. During deposition, Ag contents and deposited temperatures were varied. After deposition, a UV-VIS-NIR photometer and a Hall measurement system were used to characterize the optical and electrical properties of these films. The results showed that the Cu₂O-Ag thin films had a decreased optical transmittance with the increase of Ag contents. The resistivity was also decreased, which is most likely due to the formation of Ag phase. Through the measurement of photo-induced conductivity, it was found that, when Ag concentration was at 4 at.%, the film had the highest increase in conductivity under light irradiation. This is due to the co-existence of Ag₂O and Cu₂O. However, when deposited at a temperature higher than room temperature, the photo-induced conductivity of this film became less obvious, apparently due to the dissociation of Ag₂O. The results of Photoluminescence (PL) measurement confirmed that the Cu₂O-Ag(4 at.%) sample might produce more electron-hole pairs than other samples, which caused the increase of conductivity.     

Characterization of magnetron co-sputtered W-doped C-based films

In this paper, W-doped C-based coatings were deposited on steel and silicon substrates by RF magnetron sputtering, using W and C targets, varying the cathode power applied to the W target and the substrate bias. The chemical composition was varied by placing the substrates in a row facing the C and W targets. W content in the films increased from 1 to 2 at.% over the C target to ∼ 73 at.% over the W target. The coatings with W content lower than ∼ 12 at.% and ∼ 23 at.%, for biased and unbiased conditions, respectively, showed X-ray amorphous structures, although carbide nanocrystals must exist as shown by the detection of the WC_1−x phase in films with higher W content. C-rich films were very dense and developed a columnar morphology with increasing W content. An improvement in the hardness (from 10 GPa, up to 25 GPa) of the films was achieved either when negative substrate bias was used in the deposition, or when the WC_1−x phase was detected by X-ray diffraction. The adhesion of the coatings is very low with spontaneous spallation of those deposited with negative substrate bias higher than 45 V. Varieties in cathode power (90 W or 120 W) applied to the W target showed no observable influence on the characteristics of the films.     

Electrical and optical properties of Zn-In-Sn-O transparent conducting thin films

Indium tin oxide (ITO) is one of the widely used transparent conductive oxides (TCO) for application as transparent electrode in thin film silicon solar cells or thin film transistors owing to its low resistivity and high transparency. Nevertheless, indium is a scarce and expensive element and ITO films require high deposition temperature to achieve good electrical and optical properties. On the other hand, although not competing as ITO, doped Zinc Oxide (ZnO) is a promising and cheaper alternative. Therefore, our strategy has been to deposit ITO and ZnO multicomponent thin films at room temperature by radiofrequency (RF) magnetron co-sputtering in order to achieve TCOs with reduced indium content. Thin films of the quaternary system Zn-In-Sn-O (ZITO) with improved electrical and optical properties have been achieved.The samples were deposited by applying different RF powers to ZnO target while keeping a constant RF power to ITO target. This led to ZITO films with zinc content ratio varying between 0 and 67%. The optical, electrical and morphological properties have been thoroughly studied. The film composition was analysed by X-ray Photoelectron Spectroscopy. The films with 17% zinc content ratio showed the lowest resistivity (6.6 × 10^− 4 Ω cm) and the highest transmittance (above 80% in the visible range). Though X-ray Diffraction studies showed amorphous nature for the films, using High Resolution Transmission Electron Microscopy we found that the microstructure of the films consisted of nanometric crystals embedded in a compact amorphous matrix. The effect of post deposition annealing on the films in both reducing and oxidizing atmospheres were studied. The changes were found to strongly depend on the zinc content ratio in the films.