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1.
Hiroki Ago Izumi Tanaka Carlo M. Orofeo Masaharu Tsuji Ken‐ichi Ikeda 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(11):1226-1233
Rectangle‐ and triangle‐shaped microscale graphene films are grown on epitaxial Co films deposited on single‐crystal MgO substrates with (001) and (111) planes, respectively. A thin film of Co or Ni metal is epitaxially deposited on a MgO substrate by sputtering while heating the substrate. Thermal decomposition of polystyrene over this epitaxial metal film in vacuum gives rectangular or triangular pit structures whose orientation and shape are strongly dependent on the crystallographic orientation of the MgO substrate. Raman mapping measurements indicate preferential formation of few‐layer graphene films inside these pits. The rectangular graphene films are transferred onto a SiO2/Si substrate while maintaining the original shape and field‐effect transistors are fabricated using the transferred films. These findings on the formation of rectangular/triangular graphene give new insights on the formation mechanism of graphene and can be applied for more advanced/controlled graphene growth. 相似文献
2.
Aligned Growth of Millimeter‐Size Hexagonal Boron Nitride Single‐Crystal Domains on Epitaxial Nickel Thin Film
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Junhua Meng Xingwang Zhang Ye Wang Zhigang Yin Heng Liu Jing Xia Haolin Wang Jingbi You Peng Jin Denggui Wang Xiang‐Min Meng 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(18)
Atomically thin hexagonal boron nitride (h‐BN) is gaining significant attention for many applications such as a dielectric layer or substrate for graphene‐based devices. For these applications, synthesis of high‐quality and large‐area h‐BN layers with few defects is strongly desirable. In this work, the aligned growth of millimeter‐size single‐crystal h‐BN domains on epitaxial Ni (111)/sapphire substrates by ion beam sputtering deposition is demonstrated. Under the optimized growth conditions, single‐crystal h‐BN domains up to 0.6 mm in edge length are obtained, the largest reported to date. The formation of large‐size h‐BN domains results mainly from the reduced Ni‐grain boundaries and the improved crystallinity of Ni film. Furthermore, the h‐BN domains show well‐aligned orientation and excellent dielectric properties. In addition, the sapphire substrates can be repeatedly used with almost no limit. This work provides an effective approach for synthesizing large‐scale high‐quality h‐BN layers for electronic applications. 相似文献
3.
We report here a rapid (10 s of heating) graphene growth method that can be carried out on any desired substrate, including an insulator, thus negating the need for the transfer from the metal substrate. This technique is based on metal-induced crystallization of amorphous carbon (a-C) to graphene, and involves an ultra-thin metal layer that is less than 10 nm in thickness. Rapid annealing of a bilayer of a-C and metal deposited on the surface leads to the formation of graphene film, and to subsequent breaking-up of the thin metal layer underneath the film, thus resulting in the formation of a graphene–metal hybrid film which is both transparent and electrically conducting. Based on Raman studies, we have also systematically compared ultra-thin metal-induced crystallization behavior with a case of conventional thick metal. Based on the present investigation, it was observed that the dominant growth mechanism in ultra-thin metal-induced crystallization is nucleation controlled. 相似文献
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A. K. Kesarwani S. R. Dhakate V. N. Singh R. K. Rakshit Atul Bisht 《Fullerenes, Nanotubes and Carbon Nanostructures》2016,24(11):725-731
We have synthesized graphene film by the filtered cathodic vacuum arc (FCVA) technique and determined the number of layers in graphene films by various techniques. Amorphous carbon (a-C) films of different thicknesses (1, 2, 3, 6, 10 and 18 nm) were synthesized by the FCVA technique on Si/SiO2/Ni substrate and then annealed in vacuum at 800°C and cooled down to room temperature naturally to obtain graphene. Prepared graphene films were transferred on different substrates and characterized by the Raman spectroscopy, UV-VIS-NIR spectroscopy, high-resolution transmission electron microscopy (HRTEM), optical microscopy, atomic force microscopy (AFM) and sheet resistance to determine the number of layers present in the graphene films. Raman spectra of the prepared graphene films exhibit that there is red shift in the position of D, G and 2 D peak. The value of I2D/IG varied from 0.18 to 0.51, ID/IG varied from 0.82 to 1.02 and full width at half maximum of 2 D peak varied from 101.2 to 128.0 cm?1, for different thicknesses of graphene films, respectively. The value of transmittance decreases from 97 to 63.7% and that of sheet resistance increases from 460 to 1400 Ω/square with the increase in the thickness of the prepared graphene film. The HRTEM and AFM study revealed that the graphene synthesis from 1 nm thick a-C film possesses a single layer structure. 相似文献
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Chemical vapor deposition on copper substrates is a primary technique for synthesis of high quality graphene films over large areas. While well-developed processes are in place for catalytic growth of graphene on bulk copper substrates, chemical vapor deposition of graphene on thin films could provide a means for simplified device processing through the elimination of the layer transfer process. Recently, it was demonstrated that transfer-free growth and processing is possible on SiO(2). However, the Cu/SiO(2)/Si material system must be stable at high temperatures for high quality transfer-free graphene. This study identifies the presence of interdiffusion at the Cu/SiO(2) interface and investigates the influence of metal (Ni, Cr, W) and insulating (Si(3)N(4), Al(2)O(3), HfO(2)) diffusion barrier layers on Cu-SiO(2) interdiffusion, as well as graphene structural quality. Regardless of barrier choice, we find the presence of Cu diffusion into the silicon substrate as well as the presence of Cu-Si-O domains on the surface of the copper film. As a result, we investigate the choice of a sapphire substrate and present evidence that it is a robust substrate for synthesis and processing of high quality, transfer-free graphene. 相似文献
8.
Ni thin films with an intermediate layer of Cr were prepared by using dc magnetron sputtering under different conditions. Effects of deposition temperature, post-deposition annealing on the microstructure and the electrical characteristics were investigated. The relationship between film microstructure and its resistivity was analyzed. It was found that the crystal grains aggregated into large ones when the deposition temperature reached or exceeded 150 °C. This could be explained that high deposition temperature conduced high activation energy, which increased surface mobility of the adatoms. Annealing treatments resulted in the densification of the films. Resistivity of the films strongly depended on grain size and crystallinity. The influence of Cr intermediate layer on the resistivity was also discussed. Compared to annealing treatment, the deposition temperature exhibited larger controlling effect on film resistivity. 相似文献
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采用非平衡磁控溅射技术在不锈钢及Sip(111)基体上制备了含氢无定形碳(a-C∶H)薄膜,沉积的薄膜表面光滑,硬度高,内应力小,膜/基结合力好。利用球-盘摩擦实验机对薄膜在不同真空度(1.0×105、5.0×10-2、1.0×10-2、5.0×10-3 Pa)下的摩擦学行为进行了研究,结果表明,随着真空度的升高,薄膜的摩擦系数逐渐减小,磨损率逐渐增大。在5.0×10-3 Pa时,a-C∶H膜的摩擦学行为发生突变,此时薄膜的摩擦系数为0.005,而耐磨寿命很短。高真空中,薄膜寿命的突变可能与薄膜脱氢而结构发生变化有关。 相似文献
11.
Xuefu Zhang Tianru Wu Qi Jiang Huishan Wang Hailong Zhu Zhiying Chen Ren Jiang Tianchao Niu Zhuojun Li Youwei Zhang Zhijun Qiu Guanghui Yu Ang Li Shan Qiao Haomin Wang Qingkai Yu Xiaoming Xie 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(22)
The future electronic application of graphene highly relies on the production of large‐area high‐quality single‐crystal graphene. However, the growth of single‐crystal graphene on different substrates via either single nucleation or seamless stitching is carried out at a temperature of 1000 °C or higher. The usage of this high temperature generates a variety of problems, including complexity of operation, higher contamination, metal evaporation, and wrinkles owing to the mismatch of thermal expansion coefficients between the substrate and graphene. Here, a new approach for the fabrication of ultraflat single‐crystal graphene using Cu/Ni (111)/sapphire wafers at lower temperature is reported. It is found that the temperature of epitaxial growth of graphene using Cu/Ni (111) can be reduced to 750 °C, much lower than that of earlier reports on catalytic surfaces. Devices made of graphene grown at 750 °C have a carrier mobility up to ≈9700 cm2 V?1 s?1 at room temperature. This work shines light on a way toward a much lower temperature growth of high‐quality graphene in single crystallinity, which could benefit future electronic applications. 相似文献
12.
Ti(C, N)/a-C composite films with compositional gradient from Ti-TiN-Ti(C, N) to Ti-containing a-C layers have been prepared by closed-field unbalanced magnetron sputtering. Within the composite films, the carbon contents gradually increase and achieve maximum in the a-C layer by increasing the power applied to the graphite targets, the nitrogen contents gradually decrease to zero from Ti(C, N) layer of the interface to a-C layer of the films. In order to achieve a good combination of the mechanical and tribological properties in the composite films, a designed experimental parameter basing on various substrate rotation speeds is also selected. Results show that the compositional gradient result in the microstructure change of composite films where the Ti(C, N) layers consist of fine nanocolumnar Ti(C, N) grains and the a-C layers consist of 2-7 nm TiC nanocrystallites embedded in an amorphous C matrix. The Ti(C, N) layers also exhibit clear multilayer structure where the period thickness gradually decreases as substrate rotation speed increases. Under higher rotation speed, disappearance of the multilayer structure is accompanied with simultaneous increase in the crystallinity of Ti(C, N) layer and also the Ti(C, N) grain size. In the a-C layer, the TiC nanocrystallites embedded in the a-C matrix is produced by the high rotation speeds. The Ti(C, N)/a-C gradient composite films exhibit high microhardness values (~5000 HV) and low friction coefficient (~ 0.15), which is related to the hard Ti(C, N) layer and self-lubricate a-C layer, respectively. The combination of the Ti(C, N) layer with a-C layer increases the load and the wear resistance capacity of the composite films, which gives satisfactory friction performance in the pin-on-disk tests with a wear rate of 3.7 × 10− 17 m3/mN. 相似文献
13.
Nelea V Morosanu C Bercu M Mihailescu IN 《Journal of materials science. Materials in medicine》2007,18(12):2347-2354
The interface between nano-crystalline hydroxyapatite (HA) thin films and a titanium alloy (Ti5Al2.5Fe) has been studied by
means of Fourier transform infrared spectrophotometry and X-ray diffraction at grazing incidence. The HA thin films were deposited
by radio-frequency magnetron sputtering in low pressure dry argon on substrates kept at low temperature or heated at 550 °C.
The effect of film treatment by sputtering and annealing in humid air, as a simple, effective way of restoring the crystallinity
and stoichiometry of the HA bulk, was studied in correlation with the development of a titanium oxide layer at the film-substrate
interface. An interfacial TiO2 film grew at the interface during annealing in moist air, while a TiO2 layer diffused into the HA films when directly sputtered at 550 °C. The formation of an interfacial titanium oxide layer
was inhibited by the insertion of a crystalline TiN buffer interlayer between the substrate and the HA film. Separately, the
mechanical characteristics of the different HA films were monitored by nanoindentation to find out how they had been affected. 相似文献
14.
Large-scale uniform graphene growth was achieved by suppressing inhomogeneous carbon segregation using a single domain Ru film epitaxially grown on a sapphire substrate. An investigation of how the metal thickness affected growth and a comparative study on metals with different crystal structures have revealed that locally enhanced carbon segregation at stacking domain boundaries of metal is the origin of inhomogeneous graphene growth. Single domain Ru film has no stacking domain boundary, and the graphene growth on it is mainly caused not by segregation but by a surface catalytic reaction. Suppression of local segregation is essential for uniform graphene growth on epitaxial metal films. 相似文献
15.
磁控溅射系统在恒定Ar气压和Ar气流流量下,使用不同射频溅射功率在Si(100)衬底上分别沉积Ca薄膜;随后,800℃真空退火1 h.立方相的Ca2Si薄膜首次、单独、直接生长在Si(100)衬底上.实验结果指出,在多相共生的Ca-Si化合物中,沉积Ca薄膜时的射频溅射功率影响了立方相Ca2Si薄膜的质量;最优化的溅射功率是85 W.另外,退火温度为800℃时,有利于单一相Ca2Si的独立生长.并且,退火时间也是关键因素. 相似文献
16.
Kazunari Kuwahara Naho ItagakiKenta Nakahara Daisuke YamashitaGiichiro Uchida Kunihiro KamatakiKazunori Koga Masaharu Shiratani 《Thin solid films》2012,520(14):4674-4677
High quality epitaxial ZnO films on sapphire (110) plane have been fabricated on ZnO homo-buffer layers crystallized via solid-phase epitaxially (SPE). The SPE-ZnO films are fabricated by annealing of amorphous ZnON (a-ZnON) films deposited by RF magnetron sputtering. During annealing, the a-ZnON films are oxidized and converted to ZnO crystal. X-ray diffraction (XRD) analysis shows that the resultant films are epitaxially grown on the sapphire substrates. By using the SPE-ZnO films as homo-buffer layers, the ZnO films with high crystallinity, which are deposited by RF magnetron sputtering, are fabricated. The full width at half-maximum of XRD patterns for 2θ-ω and ω scan of (002) plane are 0.094° and 0.12°, respectively, being significantly small compared with 0.24° and 0.55° for the films without buffer layers. Thus utilizing SPE buffer layers is very promising to obtain epitaxial ZnO films with high crystallinity. 相似文献
17.
Large-area single crystal monolayer graphene is synthesized on Ni(111) thin films, which have flat terraces and no grain boundaries. The flat single-crystal Ni films are heteroepitaxially grown on MgO(111) substrates using a buffer layer technique. Low-energy electron diffraction and various spectroscopic methods reveal the long-range single crystallinity and uniform monolayer thickness of the graphene. When transferred onto an insulating wafer, continuous millimeter-scale single domain graphene is obtained. 相似文献
18.
Yu. A. Agafonov V. I. Zinenko O. V. Kononenko V. V. Saraykin 《Technical Physics Letters》2017,43(6):567-569
A new method of introducing carbon into catalytic metal films for graphene synthesis is proposed. The method is based on the phenomenon of carbon recoil atoms from a layer of methane molecules that are adsorbed on a metal film being incorporated into this film under the action of bombardment with inert gas ions. To increase the thickness of adsorbed methane layer, the substrate is cooled down to ?190°C. The proposed method has been implemented on a polycrystalline nickel film. After the final annealing, Raman spectroscopy showed the presence of numerous fragments of multilayer graphene on the film surface. 相似文献
19.
Growth of large-area single- and Bi-layer graphene by controlled carbon precipitation on polycrystalline Ni surfaces 总被引:1,自引:0,他引:1
Alfonso Reina Stefan Thiele Xiaoting Jia Sreekar Bhaviripudi Mildred S. Dresselhaus Juergen A. Schaefer Jing Kong 《Nano Research》2009,2(6):509-516
We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the
surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition (CVD). Controlling both the methane
concentration during CVD and the substrate cooling rate during graphene growth can significantly improve the thickness uniformity.
As a result, one- or two- layer graphene regions occupy up to 87% of the film area. Single layer coverage accounts for 5%–11%
of the overall film. These regions expand across multiple grain boundaries of the underlying polycrystalline Ni film. The
number density of sites with multilayer graphene/graphite (>2 layers) is reduced as the cooling rate decreases. These films
can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni film and the CVD chamber.
Here, we demonstrate the formation of films as large as 1 in2. These findings represent an important step towards the fabrication of large-scale high-quality graphene samples.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
20.
《Thin solid films》1986,144(1):21-28
Multicomponent alloy thin films based on Ni-Cr with a high silicon content were deposited in a high vacuum onto ceramic flat substrates and investigated. After annealing in air the Ni-Cr-Si films show a high stability. It has been found that the temperature coefficient of resistance has values around zero in a range of the film composition from 5 to 20 at.% Ni, from 20 to 40 at.% Cr and from 50 to 65 at.% Si. This range of the film composition is suitable for the production of metal film resistors by means of sputtering. 相似文献