Fast and uniform growth of high-quality graphene on conventional glass is of great importance for practical applications of graphene glass. We report herein a confined-flow chemical vapor deposition （CVD） approach f...Fast and uniform growth of high-quality graphene on conventional glass is of great importance for practical applications of graphene glass. We report herein a confined-flow chemical vapor deposition （CVD） approach for the high- efficiency fabrication of graphene glass. The key feature of our approach is the fabrication of a 2-4 μm wide gap above the glass substrate, with plenty of stumbling blocks; this gap was found to significantly increase the collision probability of the carbon precursors and reactive fragments between one another and with the glass surface. As a result, the growth rate of graphene glass increased remarkably, together with an improvement in the growth quality and uniformity as compared to those in the conventional gas flow CVD technique. These high-quality graphene glasses exhibited an excellent defogging performance with much higher defogging speed and higher stability compared to those previously reported. The graphene sapphire glass was found to be an ideal substrate for growing uniform and ultra-smooth aluminum nitride thin films without the tedious pre-deposition of a buffer layer. The presented confined- flow CVD approach offers a simple and low-cost route for the mass production of graphene glass, which is believed to promote the practical applications of various graphene glasses.展开更多
Laser annealing of silicon dioxide （SiO2） film formed by inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）is studied for the fabrication of low loss silicon based waveguide. The influence of ...Laser annealing of silicon dioxide （SiO2） film formed by inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO2 film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO2 film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO2 film can be significantly improved by laser annealing. Al2O3/SIO2 waveguide has been fabricated on silicon substrate with the SiO2 lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.展开更多
Carbon materials with various structures were produced via plasma-enhanced chemical vapor deposition by controlling substrate temperature and mixed gases in the atmosphere. Scanning electron microscopy（SEM）, transmi...Carbon materials with various structures were produced via plasma-enhanced chemical vapor deposition by controlling substrate temperature and mixed gases in the atmosphere. Scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, high resolution transmission electron microscopy（HRTEM） and Raman spectroscopy were employed to investigate the morphology and structure of the materials. The results show that at a low substrate temperature（100 ~C） in CHa：Ar（flow rate ratio was 100 cm3/min：10 cm3/min）, amorphous carbon formed on Si（100） that could act as a support for the growth of carbon nanobelt and layer graphene at 800 ~C. Vertically oriented multi-layer graphene nanosheets（GNs） were catalyst-free synthesized on Si and Ni foam at 800 ~C in a mixture of CHa：Ar（20 cm3/min：60, 80 and 100 cm3/min）. The capacitor character investigated by cyclic voltammetry and galvanostatic charge/discharge indicates that for the as-synthesized GNs, the electrochemical capacitance is very small（16 F/g at current density of 16 A/g）. However, having been treated in acidic solution, the GNs exhibited good capacitive behavior, with a capacitance of 166 F/g, and after 800 charge/discharge cycles at 32 A/g, the capacitance could retain about 88.4%. The enhancement of specific capacitance is attributed to the increase of specific surface area after etching treatment of them.展开更多
Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. ...Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. Therefore, we present a detailed study on the electronic properties of high-quality single-crystal monolayer graphene. The graphene is grown via CVD on copper, by using a cold-wall reactor, and then transferred to Si/SiO2. Our low-temperature magneto-transport data demonstrate that the characteristics of the single-crystal CVD graphene samples are superior to those of polycrystalline graphene and have a quality which is comparable to that of exfoliated graphene on Si/SiO2. The Dirac point in our best samples occurs at back-gate voltages lower than 10 V, and a maximum mobility of 11,000 cm2/（V.s） is attained. More than 12 flat and discernible half-integer quantum Hall plateaus occur under a high magnetic field on both the electron and hole sides of the Dirac point. At a low magnetic field, the magnetoresistance exhibits a weak localization peak. Using the theory of McCann et al., we obtain inelastic scattering lengths of 〉1 um, even at the charge neutrality point of the samples.展开更多
基金This work was financially supported by the National Basic Research Program of China （Nos. 2016YFA0200103, 2013CB932603, 2012CB933404, and 2013CB934600）, the National Natural Science Foundation of China （Nos. 51520105003 and 51432002）, the Ministry of Education （No. 20120001130010）, and the Beijing Municipal Science and Technology Planning Project （No. Z151100003315013）.
文摘Fast and uniform growth of high-quality graphene on conventional glass is of great importance for practical applications of graphene glass. We report herein a confined-flow chemical vapor deposition （CVD） approach for the high- efficiency fabrication of graphene glass. The key feature of our approach is the fabrication of a 2-4 μm wide gap above the glass substrate, with plenty of stumbling blocks; this gap was found to significantly increase the collision probability of the carbon precursors and reactive fragments between one another and with the glass surface. As a result, the growth rate of graphene glass increased remarkably, together with an improvement in the growth quality and uniformity as compared to those in the conventional gas flow CVD technique. These high-quality graphene glasses exhibited an excellent defogging performance with much higher defogging speed and higher stability compared to those previously reported. The graphene sapphire glass was found to be an ideal substrate for growing uniform and ultra-smooth aluminum nitride thin films without the tedious pre-deposition of a buffer layer. The presented confined- flow CVD approach offers a simple and low-cost route for the mass production of graphene glass, which is believed to promote the practical applications of various graphene glasses.
基金This work was supported by the National Basic Research Program of China （Nos. 2012CB315605 and 2014CB340002）, the National Natural Science Foundation of China （Grant Nos. 61210014,61321004, 61307024, 61574082 and 51561165012）, the High Technology Researeh and Development Program of China（No. 2015AA017101）, the Independent Research Program of Tsinghua University （No. 20131089364） and the Open Fund of State Key Laboratory on Integrated Optoelectronics （Nos. IOSKL2012KF08 and IOSKL2014KF09）.
文摘Laser annealing of silicon dioxide （SiO2） film formed by inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO2 film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO2 film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO2 film can be significantly improved by laser annealing. Al2O3/SIO2 waveguide has been fabricated on silicon substrate with the SiO2 lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.
基金Supported by the Natural Science Foundation of Jilin Province, China（No.201215025）, the Major Science and Technology Project of Jilin Province, China（No.llZDGG010）, the Program for Changjiang Scholars and Innovative Research Team in University of China and the ＂211＂ and ＂985＂ Project of Jilin University, China.
文摘Carbon materials with various structures were produced via plasma-enhanced chemical vapor deposition by controlling substrate temperature and mixed gases in the atmosphere. Scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, high resolution transmission electron microscopy（HRTEM） and Raman spectroscopy were employed to investigate the morphology and structure of the materials. The results show that at a low substrate temperature（100 ~C） in CHa：Ar（flow rate ratio was 100 cm3/min：10 cm3/min）, amorphous carbon formed on Si（100） that could act as a support for the growth of carbon nanobelt and layer graphene at 800 ~C. Vertically oriented multi-layer graphene nanosheets（GNs） were catalyst-free synthesized on Si and Ni foam at 800 ~C in a mixture of CHa：Ar（20 cm3/min：60, 80 and 100 cm3/min）. The capacitor character investigated by cyclic voltammetry and galvanostatic charge/discharge indicates that for the as-synthesized GNs, the electrochemical capacitance is very small（16 F/g at current density of 16 A/g）. However, having been treated in acidic solution, the GNs exhibited good capacitive behavior, with a capacitance of 166 F/g, and after 800 charge/discharge cycles at 32 A/g, the capacitance could retain about 88.4%. The enhancement of specific capacitance is attributed to the increase of specific surface area after etching treatment of them.
文摘Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. Therefore, we present a detailed study on the electronic properties of high-quality single-crystal monolayer graphene. The graphene is grown via CVD on copper, by using a cold-wall reactor, and then transferred to Si/SiO2. Our low-temperature magneto-transport data demonstrate that the characteristics of the single-crystal CVD graphene samples are superior to those of polycrystalline graphene and have a quality which is comparable to that of exfoliated graphene on Si/SiO2. The Dirac point in our best samples occurs at back-gate voltages lower than 10 V, and a maximum mobility of 11,000 cm2/（V.s） is attained. More than 12 flat and discernible half-integer quantum Hall plateaus occur under a high magnetic field on both the electron and hole sides of the Dirac point. At a low magnetic field, the magnetoresistance exhibits a weak localization peak. Using the theory of McCann et al., we obtain inelastic scattering lengths of 〉1 um, even at the charge neutrality point of the samples.
