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Y 2 O 3 films with different microstructures were deposited through radio frequency magnetron sputtering. The optical properties and the antireflection effects of the cubic and the monoclinic Y 2 O 3 films on diamond substrates were investigated. Results showed that the cubic Y 2 O 3 film had denser and more uniform grains with larger grain size. The band gap energies of the cubic and the monoclinic Y 2 O 3 films were 5.79 and 5.88 eV, respectively. This finding was mainly attributed to the decrease in grain size from 30.1 nm to 20.6 nm. Meanwhile, the reflective indices of the cubic and the monoclinic films were 1.887 and 1.817, respectively. Furthermore, the monoclinic and the cubic Y 2 O 3 films that have the same thickness generated antireflection effects on diamond at the 8–12 μm long-wave infrared (LWIR) range. However, due to the lower reflective index of the monoclinic Y 2 O 3 film compared with that of the cubic Y 2 O 3 film, the maximum antireflection effects of the Y 2 O 3 films on diamond shifted to lower wavelengths. [ABSTRACT FROM AUTHOR]

Abstract: Highly c-axis oriented ZnO film is often deposited on diamond substrates by RF magnetron sputtering and widely used for high frequency surface acoustic wave (SAW) devices. Deposition temperature is a key factor affecting the quality of the ZnO film. Different quality polished free-standing diamond films prepared by DC Arc Plasma Jet were used as the substrates to deposit ZnO films at different temperatures. Effect of the deposition temperature and the quality of the diamond films on the properties of the ZnO films were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that highly c-axis oriented ZnO films can be much easier deposited on the optical-grade diamond films with <111> preferred orientation than the tool-grade diamond films with <220> preferred orientation. The optimal deposition temperature is 200°C for highly c-axis oriented and lower roughness ZnO films. Acoustic phase velocity of more than 10,000m/s for the SAW devices based on the ZnO/optical-grade free-standing diamond films was obtained. [Copyright &y& Elsevier]

Reducing the self-heating of SiC- and GaN/SiC-based high-powered devices by integrating diamond films offers promising performance enhancement of these devices. However, such a reduction strategy faces serious problems, such as diamond nucleation on SiC and stress accumulation greater than 10 GPa. In this work, a SiN x dielectric layer (∼50 nm) was coated onto the C polar face of a 4H–SiC wafer using microwave plasma chemical vapor deposition (MPCVD) to improve direct dense diamond nucleation and growth, significantly reduce the stress, and build Si–C(SiC)⋯Si⋯C(diamond) bond bridges. This SiN x thin layer, prepared by activating Si ions under Ar/N plasma during magnetron sputtering, gave rise to local Si 3 N 4 crystal features and a low effective work function (EWF) for promoting surface dipoles with electronegative carbon-containing groups. In the H plasma environment during diamond growth, the local Si 3 N 4 crystal was amorphized, and the N atoms escaped as a result of atomic H and the high temperature. At the same time, C atoms diffused into the SiN x and formed C–Si bonds (49.7% of the total C bonds) by replacing N–Si and Si–Si, thus increasing the direct nucleation density of the diamond grains. The diamond thin film grew rapidly and uniformly, with a grain size of approximately 2 μm in mixed orientation, and the stress of the 2-inch SiC-on-diamond wafer was extremely low (to ∼0.1–0.2 GPa). In comparison, partially connected diamond grains (>10 μm) on the bare SiC in the preferential (110) orientation resulted in a film with twin-grain features and significant stress, which was associated with the hexagonal lattice interface of 4H–SiC. These results are considered the material and surface/interface bases for actively controlling wafer fabrication and enhancing the heat dissipation of SiC and GaN/SiC electronics. [ABSTRACT FROM AUTHOR]

Abstract: The current artificial joint materials need to be further improved for adhesion and service life. In the present research, the adhesion of albumen protein to CrN and CrAlN coatings on Ti alloy and Si wafer is studied via rotational shear flow. CrN and CrAlN coatings provide improved wear resistance over pure Cr. These coatings offer a potential alternative to reduce wear in artificial joints. Previous research has demonstrated that there are two factors that affect protein adhesion: surface roughness and surface chemistry. Here we study effects of material and surface properties of those coatings on protein adhesion. Experimentally, we developed a method to quantitatively evaluate the adhesive strength of proteins to the surface. Subsequently we study the interfacial mechanisms between coating surfaces and protein molecules. Results indicate that the protein adhesion depends on the substrate chemistry. The CrN and CrAlN coatings improve wear resistance with minimum to no influence with the substrate''s interaction with the proteins. [Copyright &y& Elsevier]

[Display omitted] • The La-doped Er 2 O 3 anti-reflection films was prepared by the power of magnetron sputtering. • The compound of La 2 O 3 formed along the grain boundary of the columnar crystal structure of the polycrystalline film. • The highest hardness and yield strength of the La-doped Er 2 O 3 film was two times higher than that of pure Er 2 O 3 film. • The transmittance of the La-doped Er 2 O 3 anti-reflection films only decreased 1% after erosion. The composition and microstructure consisting of anti-reflection films was obtained by the power of magnetron sputtering. X-ray photoelectron spectroscopy (XPS) and High-resolution transmission electron microscopy (HRTEM) provided evidence to support that the doping La element exists as oxide in the grain boundaries of the matrix Er 2 O 3 films. The undoped and La-doped Er 2 O 3 films show a columnar crystal structure of the main cubic (2 2 2) plane. Twinning and a large number of dislocations show up in the undoped Er 2 O 3 films due to the competitive growth of the columnar crystal. In addition, the La-doped Er 2 O 3 films show a lower roughness (RMS) value in comparison with undoped Er 2 O 3 films. The grain size of columnar crystals decreases significantly with increasing La concentration in the La-doped Er 2 O 3 films. The fine grains resulted in the La-doped Er 2 O 3 films developing high mechanical and impact resistance properties, with an increase in hardness from 12.6 ± 2.1 GPa to 26.1 ± 3.4 GPa and the eroding area rate decreasing from 38.9 % to 1.9 %. Moreover, the La-doped Er 2 O 3 anti-reflection films on the chemical vapor deposition (CVD) diamond substrate maintained 74 % transmittance in the long-wavelength infrared range of 8–12 μm after sand eroding. [ABSTRACT FROM AUTHOR]

Y 2 O 3 anti-reflection films were deposited on freestanding CVD diamond substrates by radio frequency magnetron sputtering. The thermal shock resistance and oxidation resistance of Y 2 O 3 /diamond/Y 2 O 3 samples at 727 °C and 800 °C in atmospheric air were investigated. No delamination of the Y 2 O 3 films occurred after thermal shock, thereby demonstrating extreme adhesion to freestanding diamond substrates. After thermal shock, Y atoms in the films were almost fully oxidized. Moreover, the majority of monoclinic phase in the Y 2 O 3 films transformed into cubic phase, crystallinity was enhanced, and the average grain size significantly increased. The maximum transmittance in the 8–12 μm long-wave IR range of the Y 2 O 3 /diamond/Y 2 O 3 samples increased from 81.3% ± 0.3% to 84.7% ± 0.2% and 83.6% ± 0.4%. These findings indicated that the Y 2 O 3 anti-reflection films displayed good resistance to thermal shock and provided sufficient protection for diamond substrates against elevated temperature oxidation. [ABSTRACT FROM AUTHOR]

• 21% increase of maximum transmittance of Er2O3 films deposited on diamond coatings. • Negative electrical bias induces the formation of monoclinic Er2O3 on Si(110). • Monoclinic Er2O3 effectively improve the transmittance of the diamond coating. Er 2 O 3 anti-reflection films were deposited on the surface of the chemical vapor deposited diamond films and Si(100) substrates by radio frequency magnetron sputtering. The microstructure of the Er 2 O 3 thin films and the interfacial layer were investigated by means of scanning electron microscopy, X-ray diffraction, atomic force microscopy and transmission electron microscopy. The refractive index, hardness and transmittance of the films were measured by ellipsometry, nanoindentation measurements, and Fourier transformed infrared spectroscopy. Results revealed that the bias induces the formation of a monoclinic phase and the nucleation of the Er 2 O 3 thin films is mainly observed along the (222) plane. A high-resolution TEM image revealed a 2.5-nm-thick amorphous layer at the interface between the Si substrate and Er 2 O 3 film. Notably, monoclinic Er 2 O 3 films can considerably improve the transmittance of the diamond film in the long-wavelength infrared range of 8–12 μm via the reduction of the refractive index. However, the introduction of the monoclinic phase led to the decrease of the hardness and elastic modulus of the films; hence, controlling a suitable amount of the monoclinic phase may play an extremely important role in the mechanical and optical properties of the Er 2 O 3 films. [ABSTRACT FROM AUTHOR]

Nd 2 O 3 film is a functional film with great potential application value. In this paper, thinNd 2 O 3 film was prepared on the surface of Si substrates using RF magnetron reactive sputtering. Nd 2 O 3 film with different crystal structures were controlled by changing the deposition temperature. The results show that the Nd 2 O 3 film with a cubic structure can be obtained at 150 °C, while a hexagonal structure appears at 250 °C and above. The refractive indices of the cubic and hexagonal Nd 2 O 3 films were 1.736 and 2.130, respectively. Moreover, the principle of the influence of deposition temperature on the refractive index of the film was illustrated. The hardness and the elastic modulus of the cubic Nd 2 O 3 film were 6.3 GPa and 102 GPa, respectively, which are much lower than the 9.9 GPa and 145 GPa of the hexagonal Nd 2 O 3 film. In addition, with a double-sided cubic Nd 2 O 3 film, the maximum transmittance of the diamond film reached 87.54%. The results show that the Nd 2 O 3 film is an anti-reflection film suitable for optical applications. • Nd 2 O 3 films with cubic and hexagonal structures were prepared, respectively. • The mechanical and optical properties of two kinds of Nd 2 O 3 films were compared. • Hexagonal Nd 2 O 3 film shows hardness of 9.9 GPa and elastic modulus of 145 GPa. • Diamond presents the maximum transmittance of 87.54% at 11.2 μm with Nd 2 O 3 films. [ABSTRACT FROM AUTHOR]

For AlN/diamond structure, the crystal quality of diamond substrates is of great importance for the epitaxial growth of AlN. In this paper, c‐axis‐oriented AlN films are deposited on diamond with different crystal quality by radio frequency (RF) reactive magnetron sputtering. The effects of the microstructure of diamond substrates on the orientation of AlN are studied. The results show that the crystal quality of the diamond films greatly affects the growth behavior of AlN. The surface defects of diamond, such as the amorphous phase, will cause the growth direction of AlN to deviate from the c‐axis, resulting in the disorder of grain orientation. Meanwhile, diamond crystal orientation also has influence on the growth of AlN. The (111) oriented grains of diamond are beneficial to the c‐axis growth of AlN. The interface of AlN nucleation and initial growth plays a vital role in final performance of the films, where there is a transition zone from randomly oriented AlN grains to c‐axis‐oriented grains. The suitable diamond substrate can eliminate the transition zone, and can lead to AlN films with high‐degree c‐axis orientation. For the AlN/diamond structure, there is a transition zone from randomly oriented AlN grains to c‐axis‐oriented grains in the interface of AlN nucleation and initial growth. The high crystalline quality and (111) oriented grains of diamond can eliminate the transition zone, which can lead to the strong c‐axis orientation of AlN films. [ABSTRACT FROM AUTHOR]