Effects of sputtering pressure on nanostructure and nanomechanical properties of AlN films prepared by RF reactive sputtering

Wurtzite aluminum nitride（AlN） films were deposited on Si（100） wafers under various sputtering pressures by radio-frequency（RF） reactive magnetron sputtering. The film properties were investigated by XRD, SEM, AFM, XPS and nanoindenter techniques. It is suggested from the XRD patterns that highly c-axis oriented films grow preferentially at low pressures and the growth of（100） planes are preferred at higher pressures. The SEM and AFM images both reveal that the deposition rate and the surface roughness decrease while the average grain size increases with increasing the sputtering pressure. XPS results show that lowering the sputtering pressure is a useful way to minimize the incorporation of oxygen atoms into the AlN films and hence a film with closer stoichiometric composition is obtained. From the measurement of nanomechanical properties of AlN thin films, the largest hardness and elastic modulus are obtained at 0.30 Pa.

OPTICAL CHARACTERIZATION OF TiO_2 THIN FILM ON SILICON SUBSTRATE DEPOSITED BY DC REACTIVE MAGNETRON SPUTTERING

TiO2 thin film has attracted considerable attention in recent years, due to its different refractive index and transparency with amorphous and different crysta ls in the visible and near-infrared wavelength region, high dielectric constant, wide band gap, high wear resistance and stability, etc, for which make it being used in many fields. This paper aims to investigate the optical characterizatio n of thin film TiO2 on silicon wafer. The TiO2 thin films were prepared by DC re active magnetron sputtering process from Ti target. The reflectivity of the film s was measured by UV-3101PC, and the index of refraction (n) and extinction coef ficient (k) were measured by n & k Analyzer 1200.

STUDY ON Ni-Cr SYSTEM SOLAR SELECTIVE THIN FILMS PREPARED BY MAGNETRON REACTIVE SPUTTERING PROCESS

Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactive sputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as target material and copper sheets as substrate. Using SEAL Spectrophotometer and Talystep to analyze the relations between the selective characteristic and the structure, the formation and the thickness of the thin films. The aim is to obtain good solar selective thin films with high absorptance and low emittance, which is applied to flat plate solar heat collectors.

Reactive Magnetron Sputtering of CN_x Thin Films on β-Si_3N_4 Substrates

Carbon nitride CN. thin films have been deposited on polycrystalline β-Si3N4 substrates by un-balanced magnetron sputtering in a nitrogen discharge. Both the film deposition rate and the nitrogen concentration decrease with substrate temperature increase in the range of 100~400℃The maximum of nitrogen content is 40 at. pct. Raman spectroscopy and atomic force mi-croscopy were used to characterize the bonding, microstructure and surface roughness of the films. Nanoindentation experiments exhibit a higher hardness of 70 GPa and an extremely elas-tic recovery of 85% at higher substrate temperature.

Wafer‑Scale Ag_(2)S‑Based Memristive Crossbar Arrays with Ultra‑Low Switching‑Energies Reaching Biological Synapses

Memristive crossbar arrays(MCAs)offer parallel data storage and processing for energy-efficient neuromorphic computing.However,most wafer-scale MCAs that are compatible with complementary metal-oxide-semiconductor(CMOS)technology still suffer from substantially larger energy consumption than biological synapses,due to the slow kinetics of forming conductive paths inside the memristive units.Here we report wafer-scale Ag_(2)S-based MCAs realized using CMOS-compatible processes at temperatures below 160℃.Ag_(2)S electrolytes supply highly mobile Ag+ions,and provide the Ag/Ag_(2)S interface with low silver nucleation barrier to form silver filaments at low energy costs.By further enhancing Ag+migration in Ag_(2)S electrolytes via microstructure modulation,the integrated memristors exhibit a record low threshold of approximately−0.1 V,and demonstrate ultra-low switching-energies reaching femtojoule values as observed in biological synapses.The low-temperature process also enables MCA integration on polyimide substrates for applications in flexible electronics.Moreover,the intrinsic nonidealities of the memristive units for deep learning can be compensated by employing an advanced training algorithm.An impressive accuracy of 92.6%in image recognition simulations is demonstrated with the MCAs after the compensation.The demonstrated MCAs provide a promising device option for neuromorphic computing with ultra-high energy-efficiency.

Study of hysteresis behavior in reactive sputtering of cylindrical magnetron plasma

In order to make sufficient use of reactive cylindrical magnetron plasma for depositing compound thin films, it is necessary to characterize the hysteresis behavior of the discharge. Cylindrical magnetron plasmas with different targets namely titanium and aluminium are studied in an argon/oxygen and an argon/nitrogen gas environment respectively. The aluminium and titanium emission lines are observed at different flows of reactive gases. The emission intensity is found to decrease with the increase of the reactive gas flow rate. The hysteresis behavior of reactive cylindrical magnetron plasma is studied by determining the variation of discharge voltage with increasing and then reducing the flow rate of reactive gas,while keeping the discharge current constant at 100 m A. Distinct hysteresis is found to be formed for the aluminium target and reactive gas oxygen. For aluminium/nitrogen, titanium/oxygen and titanium/nitrogen, there is also an indication of the formation of hysteresis; however, the characteristics of variation from metallic to reactive mode are different in different cases. The hysteresis behaviors are different for aluminium and titanium targets with the oxygen and nitrogen reactive gases, signifying the difference in reactivity between them. The effects of the argon flow rate and magnetic field on the hysteresis are studied and explained.

Effects of Power Density and Post Annealing Process on the Microstructure and Wettability of TiO_2 Films Deposited by Mid-frequency Magnetron Reactive Sputtering

The relationship of ＂preparation parameters-microstructures-wettability＂ of TiO2 films was reported. In this work, TiO2 films were deposited onto glass and silicon substrates by using mid-frequency dual magnetron sputtering technique at ambient temperature with various power densities and deposition time. After deposition, the films were heat treated at different annealing temperatures. X-ray diffraction （XRD）, Raman spectroscopy, and field-emission scanning electron microscopy （FE-SEM） were utilized to characterize TiO2 films. The wettability of the films was evaluated by water contact angle measurement. The phase transition temperature of TiO2 films depended on the power density. It was demonstrated that wettability was strongly structure dependent and the film with the thickness of 610 nm （the power density was 2.22 W/cm^2） showed the lowest contact angle （8°）. It can be concluded that smaller crystallite size, the rutile phase with （110） face being parallel to the surface, and tensile stress favored the hydrophilicity of the TiO2 films.

Effect of substrate temperature on microstructure and optical properties of single-phased Ag_2O film deposited by using radio-frequency reactive magnetron sputtering method

Using a radio-frequency reactive magnetron sputtering technique, a series of the single-phased Ag20 films are deposited in a mixture of oxygen and argon gas with a flow ratio of 2：3 by changing substrate temperature （Ts）. Effects of the Ts on the microstructure and optical properties of the films are investigated by using X-ray diffractometry, scanning electron microscopy and spectrophotometry. The single-phased Ag20 films deposited at values of Ts below 200℃ are （111） preferentially oriented, which may be due to the smallest free energy of the （111） crystalline face. The film crystallization becomes poor as the value of Ts increases from 100℃ to 225℃. In particular, the Ag20 film deposited at Ts=225℃ loses the （111） preferential orientation. Correspondingly, the film surface morphology obviously evolves from a uniform and compact surface structure to a loose and gullied surface structure. With the increase of Ts value, the transmissivity and the reflectivity of the films in the transparent region are gradually reduced, while the absorptivity gradually increases, which may be attributed to an evolution of the crystalline structure and the surface morphology of the films.

Preparation of CeO_2 Buffer Layer on Cube Textured Nickel Substrate by Reactive Sputtering

The buffer layer CeO2 films were grown on cube textured metallic Ni substrates by using reactive magnetrun sputtering. Ar/H2 mixed atmosphere, which effectively inhibited the formation of NiO, was used as pre-depositing gas before CeO2 films were grown in Ar and 02. At 700 ℃ under the total pressure of 26 Pa,the pure c-axis orientation tilm was obtained. X-ray θ-2θscan, pole figure and φ-scan were used to observe the microstructure of the buffer layer. The resuits show that CeO2 film has strong cube texture and the FWHM is 9°. In addition, the CeO2 film is dense and crack-free.

Modeling for V–O_2 reactive sputtering process using a pulsed power supply

In this article, we present a time-dependent model that enables us to describe the dynamic behavior of pulsed DC reactive sputtering and predict the film compositions of VOx prepared by this process. In this modeling, the average current J is replaced by a new parameter of Jeff. Meanwhile, the four species states of V, V2O3, VO2, and V2O5 in the vanadium oxide films are taken into consideration. Based on this work, the influences of the oxygen gas supply and the pulsed power parameters including the duty cycle and frequency on film compositions are discussed. The model suggests that the time to reach process equilibrium may vary substantially depending on these parameters. It is also indicated that the compositions of VOx films are quite sensitive to both the reactive gas supply and the duty cycle when the power supply works in pulse mode. The ＇steady-state＇ balance values obtained by these simulations show excellent agreement with the experimental data, which indicates that the experimentally obtained dynamic behavior of the film composition can be explained by this time-dependent modeling for pulsed DC reactive sputtering process. Moreover, the computer simulation results indicate that the curves will essentially yield oscillations around the average value of the film compositions with lower pulse frequency.

Deposition of Aluminium Oxide Films by Pulsed Reactive Sputtering

Pulsed reactive sputtering is a novel process used to deposit some compound films, which are not deposited by traditional D.C. reactive sputtering easily. In this paper some experimental results about the deposition of Al oxide films by pulsed reactive sputtering are presented. The hysteresis phenomenon of the sputtering voltage and deposition rate with the change of oxygen flow during sputtering process are discussed.

Evolution of the structural and optical properties of silver oxide films with different stoichiometries deposited by direct-current magnetron reactive sputtering

Nitrogen doping of silver oxide （AgxO） film is necessary for its application in transparent conductive film and diodes because intrinsic AgxO film is a p-type semiconductor with poor conductivity. In this work, a series of AgxO films is deposited on glass substrates by direct-current magnetron reactive sputtering at different flow ratios （FRs） of nitrogen to 02. Evolutions of the structure, the refiectivity, and the transmissivity of the film are studied by X-ray diffractometry and sphectrophotometry, respectively. The specular transmissivity and the specular refiectivity of the film decreasing with FR increasing can be attributed to the evolution of the phase structure of the film. The nitrogen does not play the role of an acceptor dopant in the film deposition.

Effects of the sputtering power on the crystalline structure and optical properties of the silver oxide films deposited using direct-current reactive magnetron sputtering

This paper reports that a series of silver oxide （AgzO） films are deposited on glass substrates by direct-current reactive magnetron sputtering at a substrate temperature of 250 ℃ and an oxygen flux ratio of 15：18 by modifying the sputtering power （SP）. The AgxO films deposited apparently show a structural evolution from cubic biphased （AgO ＋ Ag20） to cubic single-phased （Ag20）, and to biphased （Ag20 ＋ AgO） structure. Notably, the cubic single-phased Ag20 fihn is deposited at the SP = 105 W and an AgO phase with （220） orientation discerned in the Ag^O films deposited using the SP 〉 105 W. The transmissivity and refiectivity of the AgxO films in transparent region decrease with the increase the SP, whereas the absorptivity inversely increases with the increase of the SP. These results may be due to the structural evolution and the increasing film thickness. A redshift of the films＇ absorption edges determined in terms of Tauc formula clearly occurs from 3.1 eV to 2.73 eV with the increase of the SP.

Reactive magnetron sputtering of germanium carbide films at different substrate temperature

To explore the relationship between the chemical bonding and mechanical properties for germanium carbide (Ge1-xCx) films,the Ge1-xCx films are prepared via reactive magnetron sputtering in a mixture of CH4/Ar discharge,and their composition,chemical bonding and hardness were investigated as a function of substrate temperature (Ts). The results show that Ts remarkably influences the chemical bonding of Ge1-xCx film,which results in a pronounced change in the film hardness. As Ts increases from ambient (60 ℃) to 500 ℃,the Ge content in the film gradually increases,which promotes forming sp3 C-Ge bonds in the film at the expense of sp2C-C bonds. Furthermore,it is found that with increasing Ts the fraction of C-H bonds in Ge1-xCx film gradually decreases,which is attributed to an enhancement in the desorption rate of C-Hn(n=1,2,3) species decomposed from methane. The transition from graphite-like sp2 C-C to diamond-like sp3C-Ge bonds as well as the reduction in C-H bonds in the film with increasing Ts promotes forming the compact three-dimensional network structure,which significantly enhances the hardness of the film from 5.8 to 10.1 GPa.

Polycrystalline ZnO Films Deposited on Glass by RF Reactive Sputtering

Polycrystalline ZnO films were prepared on glass wafer using Zn targets by radio frequency(RF)reactive sputtering technique under different deposition conditions.X-ray diffraction (XRD) and optical transmittance spectrum were employed to analyze the structure and optical character of the films.The strain and stress in films, as well as the packing density are calculated in terms of refractive index of films measured with an elliptic polarization analyzer.It is the deposition conditions that have great effects on the structural and optical properties of ZnO films.Under the optimal conditions,the only evident peak in XRD spectrum was (002) peak with the full width at half maximum (FWHM) of 0.20° showing the grain size of 42.8 nm.The packing density,the stress in (002) plane and the average optical transmittance in the visible region were about 97%,-1.06×10~9 N/m^2 and 92%, respectively.

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films （Cr/a-C：H） are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C：H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load （Lc） of 36 N for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C：H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C：H film should be a good candidate for engineering applications.

谷氨酸、CRP及S-100β蛋白水平与脑出血患者预后的关系

目的:分析谷氨酸、C反应蛋白(CRP)及S-100β蛋白水平与脑出血患者预后的关系。方法:选择2021年1月—2023年12月南昌大学第四附属医院收治的80例脑出血患者,患者入院后采集血样,测定血清谷氨酸、CRP及S-100β蛋白水平。随访90 d,采用格拉斯哥预后量表(GPS)进行预后评价,根据GPS评分分为预后不良组(1~3分)、预后良好组(4~5分),比较两组谷氨酸、CRP及S-100β蛋白水平,分析谷氨酸、CRP及S-100β蛋白水平与预后的相关性,采用受试者操作特征(ROC)曲线分析这些生物标志物对患者预后预测的价值。结果:在80例脑出血患者中,预后不良发生率为43.75%(35/80)。预后不良组血清谷氨酸、CRP及S-100β蛋白水平均高于预后良好组(P<0.05)。点二列相关系数分析结果显示,谷氨酸、CRP及S-100β蛋白与预后呈正相关(r=0.709、0.764、0.654,P<0.05)。Pearson相关系数分析显示,谷氨酸、CRP与S-100β蛋白呈正相关(r=0.361、0.431,P<0.001)。ROC曲线显示,谷氨酸、CRP、S-100β蛋白对患者预后预测的AUC分别为0.912、0.945、0.881,有一定预测价值。结论:谷氨酸、CRP及S-100β蛋白水平与脑出血患者的预后呈正相关,并具有一定的预测价值,在评估脑出血患者的预后时,这些可作为重要的参考指标之一。

Properties of Reactive Magnetron Sputtered ITO Films without in-situ Substrate Heating and Post-deposition Annealing

Indium tin oxide (ITO) films were prepared on polyester, Si and glass substrate with relatively high deposition rate of above 0.9 nm/s by DC reactive magnetron sputtering technique at the sputtering pressure of 0.06 Pa system, respectively. The dependence of resistivity on deposition parameters, such as deposition rate, target-to-substrate distance (TSD), oxygen flow rate and sputtering time (thickness), has been investigated, together with the structural and the optical properties. It was revealed that all ITO films exhibited lattice expansion. The resistivity of ITO thin films shows significant substrate effect: much lower resistivity and broader process window have been reproducibly achieved for the deposition of ITO films onto polyester rather than those prepared on both Si and glass substrates. The films with resistivity of as low as 4.23 x 10^-4 Ω.cm and average transmittance of ～78% at wavelength of 400～700 nm have been achieved for the films on polyester at room temperature.

Decreased osteogenesis of adult mesenchymal stem cel s by reactive oxygen species under cyclic stretch: a possible mechanism of age related osteoporosis

Age related defect of the osteogenic differentiation of mesenchymal stem cells（MSCs） plays a key role in osteoporosis. Mechanical loading is one of the most important physical stimuli for osteoblast differentiation.Here, we compared the osteogenic potential of MSCs from young and adult rats under three rounds of 2 h of cyclic stretch of 2.5% elongation at 1 Hz on 3 consecutive days. Cyclic stretch induced a significant osteogenic differentiation of MSCs from young rats, while a compromised osteogenesis in MSCs from the adult rats.Accordingly, there were much more reactive oxygen species（ROS） production in adult MSCs under cyclic stretch compared to young MSCs. Moreover, ROS scavenger N-acetylcysteine rescued the osteogenic differentiation of adult MSCs under cyclic stretch. Gene expression analysis revealed that superoxide dismutase 1（SOD1） was significantly downregulated in those MSCs from adult rats. In summary, our data suggest that reduced SOD1 may result in excessive ROS production in adult MSCs under cyclic stretch, and thus manipulation of the MSCs from the adult donors with antioxidant would improve their osteogenic ability.

Florid reactive periostitis ossificans of the humerus: Case report and differential diagnosis of periosteal lesions of long bones

A case of florid reactive periostitis ossificans(RPO) arising in a long bone is presented. This is a rare bone proliferation with a pronounced periosteal reaction. Less than 100 cases have been described in the literature with far fewer outside the bones of the hand, feet, fingers, and toes. Although the etiology is unknown, a relationship to preceding trauma is suggested. The imaging and histologic features show an overlap with other bone lesions including bizarre parosteal osteochondromatous proliferation, subungual exostosis, and malignant surface tumors of bone and cartilage which include, periosteal and parosteal osteosarcoma. It is important to recognize the clinical presentation and diagnostic features of RPO as a benign entity so that it is not mistaken for a more aggressive neoplasm. We present a case of a right distal humeral lesion that on histopathological review revealed florid RPO. This diagnosis was not suspected on imaging studies, but was made on open biopsy of the mass. The patient remains disease free, years postoperatively. In addition to presenting this unique case report, we review the pertinent literature, and offer a differential diagnosis and treatment strategy for its management.