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One-step supramolecular preorganization constructed crinkly graphitic carbon nitride nanosheets with enhanced photocatalytic activity

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Journal of Materials Science & Technology 2022年第9期104卷 155-162页

作者： Songcan Wang Yuelin Li Xin Wang Guohao Zi Chenyang Zhou Boyan Liu Gang Liu Lianzhou Wang Wei Huang Frontiers Science Center for Flexible Electronics Xi’an Institute of Flexible Electronics(IFE)Xi’an Institute of Biomedical Materials&EngineeringNorthwestern Polytechnical University127 West Youyi RoadXi’an 710072China Honors College Northwestern Polytechnical University127 West Youyi RoadXi’an 710072China Nanomaterials Centre School of Chemical Engineering and Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandQLD 4072Australia Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China

Here we report a new one-step thermal polycondensation process to form crinkly graphitic carbon nitride nanosheets(CGCNNs)via supramolecular preorganization,using a mixture of urea and melamine as the starting material.Systematical studies reveal that the newly developed CGCNNs significantly strengthen the optical absorption,widen the bandgap,and increase the hall mobility and carrier density compared to that of its bulk counterpart,regardless of the similar chemical composition and structure.As a result,the photocatalytic hydrogen production rate is improved by 7 times.Moreover,Na doping of CGCNNs can further promote its photocatalytic activity,leading to an excellent photocatalytic hydrogen production rate of 250.9μmol h^(–1),which is approximately 10.5 times higher than its bulk counterpart.Moreover,an impressive apparent quantum efficiency of 19.12%is achieved at 420 nm.This study provides a facile strategy for the design of efficient low-cost carbon-nitride-based photocatalysts for solar fuel production.

关键词： Carbon nitride Supramolecular preorganization hall mobility Na doping Solar hydrogen

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Modulation of electrical and optical properties of gallium-doped ZnO films by radio frequency magnetron sputtering

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Chinese Physics B 2012年第6期21卷 478-484页

作者：梁爽梅增霞杜小龙 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Ga-doped ZnO （GZO） films are prepared on amorphous glass substrates at room temperature by radio frequency magnetron sputtering. The results reveal that the gallium doping efficiency, which will have an important influence on the electrical and optical properties of the film, can be governed greatly by the deposition pressure and film thickness. The position shifts of the ZnO （002） peaks in X-ray diffraction （XRD） measurements and the varied hall mobility and carrier concentration confirms this result. The low hall mobility is attributed to the grain boundary barrier scattering. The estimated height of barrier decreases with the increase of carrier concentration, and the trapping state density is nearly constant. According to defect formation energies and relevant chemical reactions, the photoluminescence （PL） peaks at 2.46 eV and 3.07 eV are attributed to oxygen vacancies and zinc vacancies, respectively. The substitution of more Ga atoms for Zn vacancies with the increase in film thickness is also confirmed by the PL spectrum. The obvious blueshift of the optical bandgap with an increase of carrier concentration is explained well by the Burstein Moss （BM） effect. The bandgap difference between 3.18 eV and 3.37 eV, about 0.2 eV, is attributed to the metal-semiconductor transition.

关键词： doping efficiency hall mobility photoluminescence Burstein-Moss effect

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Thermodynamic criterion for searching high mobility two-dimensional electron gas at KTaO_(3)interface

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Chinese Physics B 2021年第7期30卷 70-73页

作者：时文潇张慧齐少锦张金娥黄海林沈保根陈沅沙孙继荣 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Fujian Innovation Academy Chinese Academy of SciencesFuzhou 350108China Songshan Lake Materials Laboratory Dongguan 523808China Spintronics Institute University of JinanJinan 250022China

Two-dimensional electron gases(2 DEGs)formed at the interface between two oxide insulators present a promising platform for the exploration of emergent phenomena.While most of the previous works focused on SrTiO_(3-)based 2 DEGs,here we took the amorphous-ABO_(3)/KTaO_(3)system as the research object to study the relationship between the interface conductivity and the redox property of B-site metal in the amorphous film.The criterion of oxide-oxide interface redox reactions for the B-site metals,Zr,Al,Ti,Ta,and Nb in conductive interfaces was revealed:the formation heat of metal oxide,ⅢH_(f)^(o),is lower than-350 kJ/(mol O)and the work function of the metalΦis in the range of 3.75 eVmobility of the two-dimensional electron gas that formed at the corresponding amorphous-ABO_(3)/KTaO_(3)interface.This finding paves the way for the design of high-mobility all-oxide electronic devices.

关键词： two-dimensional electron gas oxygen vacancies thermodynamic criterion hall mobility

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Different temperature dependence of carrier transport properties between Al_xGa_(1-x)N/In_yGa_(1-y)N/GaN and Al_xGa_(1-x)N/GaN heterostructures

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Chinese Physics B 2011年第5期20卷 374-378页

作者：宋杰许福军黄呈橙林芳王新强杨志坚沈波 State Key Laboratory of Artificial Microstructure and Mesoscopic Physics School of PhysicsPeking University

The temperature dependence of carrier transport properties of Alx Gal-xN/InyGal-yN/CaN and AlzGal-xN/GaN heterostructures has been investigated. It is shown that the hall mobility in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures is higher than that in Alo.25Gao.75N/GaN heterostructures at temperatures above 500 K, even the mobility in the former is much lower than that in the latter at 300 K. More importantly, the electron sheet density in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures decreases slightly, whereas the electron sheet density in Al0.25Gao.75N/CaN heterostructures gradually increases with increasing temperature above 500 K. It is believed that an electron depletion layer is formed due to the negative polarization charges at the Iny Can-yN/GaN heterointerface induced by the compressive strain in the InyCal-yN channel, which effectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.

关键词： temperature dependence hall mobility parallel conductivity

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Effect of surface morphology on the electron mobility of epitaxial graphene grown on 0° and 8° Si-terminated 4H-SiC substrates

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Chinese Physics B 2012年第9期21卷 466-469页

作者：李佳王丽冯志红蔚翠刘庆彬敦少博蔡树军 Science and Technology on ASIC Lab. Hebei Semiconductor Research Institute Information Center of Science and Technology Science and Technology on ASIC Lab. Hebei Semiconductor Research Institute

Graphene with different surface morphologies were fabricated on 8°-off-axis and on-axis 4H-SiC（0001） substrates by high-temperature thermal decompositions. Graphene grown on Si-terminated 8°-off-axis 4H-SiC（0001） shows lower hall mobility than the counterpart of on-axis SiC substrates. The terrace width is not responsible for the different electron mobility of graphene grown on different substrates, as the terrace width is much larger than the mean free path of the electrons. The electron mobility of graphene remains unchanged with an increasing terrace width on Si- terminated on-axis SiC. Interface scattering and short-range scattering are the main factors affecting the mobility of epitaxial graphene. After the optimization of the growth process, the hall mobility of the graphene reaches 1770 cm^2/V.s at a carrier density of 9.8.×10^12 cm^-2. Wafer-size graphene was successfully achieved with an excellent double-layer thickness uniformity of 89.7% on a 3-inch SiC substrate.

关键词： graphene morphology hall mobility 3-inch SiC substrate

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Properties of Resistivity, Reflection and Absorption Related to Structure of ITO Films

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Journal of Materials Science & Technology 2012年第4期28卷 325-328页

作者： Yipeng Chao Wu Tang Xuehui Wang State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technologyof ChinaChengdu 610054China

Indium tin oxide （ITO） films were fabricated on polyethylene terephthalate （PET） substrate at room temperature using dc magnetron sputtering technique with different sputtering powers. The structural, electrical and optical properties were investigated by X-ray diffraction （XRD）, hall effect, reflection and transmission, respectively. XRD patterns show gradual enhancement of crystalline quality with increasing sputtering power. Significant improvement of hall mobility due to the reduction of defects was observed though the carrier density varied slightly. Simultaneously, the mean transmission in visible light range decreased severely with increasing sputtering power. Slight move toward shorter-wavelength side of absorption peak was due to the variation of plasma wavelength. The reflection increase of near-infrared light originated from the decrease of resistivity. Finally, band gap was obtained using Tauc＇s relation and it was consistent with Burstein-Moss shift.

关键词： Crystalline quality hall mobility Absorption

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Properties of Boron-doped μc-Ge:H Films Deposited by Hot-wire CVD

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Journal of Wuhan University of Technology(Materials Science) 2015年第3期30卷 516-519页

作者：黄海宾沈鸿烈 WU Tianru LU Linfeng TANG Zhengxia SHEN Jiancang Institute of Photovoltaics Nanchang University College of Materials Science & Technology Nanjing University of Aeronautics & Astronautics National Laboratory of Solid State Microstructure and Department of Physics Nanjing University

Boron-doped hydrogenated microcrystalline Germanium （lac-Ge：H） films were deposited by hot-wire CVD. H2 diluted G-ell4 and B2H6 were used as precursors and the substrate temperature was kept at 300 ℃. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and hall Effect measurement with Van der Pauw method. It is found that the films are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge （220）. The conductivity of the films increases and tends to be saturated with increasing diborane-to-germane ratio RB2H6. All the hall mobilities of the samples are larger than 3.8 cmZV-1·s-1. A high conductivity of

关键词： Boron pc-Ge：H film HWCVD crystalline fraction conductivity hall mobility

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Effect of substrate temperature on the growth and properties of boron-doped microcrystalline silicon films

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Chinese Physics B 2006年第1期15卷 213-218页

作者：雷青松吴志猛耿新华赵颖孙健奚建平 Institute of Micro and Nano Science and Technology Shanghai Jiaotong University Shanghai 200030 China Institute of Photo-Electronics Nankai University Tianjin 300071 China

Highly conductive boron-doped hydrogenated mieroerystalline silicon （μc-Si：H） films are prepared by very high frequency plasma enhanced chemical vapour deposition （VHF PECVD） at the substrate temperatures （Ts） ranging from 90℃ to 270℃. The effects of Ts on the growth and properties of the films are investigated. Results indicate that the growth rate, the electrical （dark conductivity, carrier concentration and hall mobility） and structural （crystallinity and grain size） properties are all strongly dependent on Ts. As Ts increases, it is observed that 1） the growth rate initially increases and then arrives at a maximum value of 13.3 nm/min at Ts=210℃, 2） the crystalline volume fraction （Xc） and the grain size increase initially, then reach their maximum values at TS=140℃, and finally decrease, 3） the dark conductivity （σd）, carrier concentration and hall mobility have a similar dependence on Ts and arrive at their maximum values at Ts-190℃. In addition, it is also observed that at a lower substrate temperature Ts, a higher dopant concentration is required in order to obtain a maximum σd.

关键词： boron-doped μc-Si：H films VHF PECVD crystallinity carrier concentration hall mobility

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