杨国伟
( 1)低维材料物理与化学;( 2 )纳米材料与纳米结构;(3)材料生长的热力学理论
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- 姓名:杨国伟
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学术头衔:
博士生导师
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学科领域:
材料科学基础学科
- 研究兴趣:( 1)低维材料物理与化学;( 2 )纳米材料与纳米结构;(3)材料生长的热力学理论
杨国伟,男,2000年6月毕业于清华大学材料科学与工程系材料物理与化学专业获博士学位。2000年6月――2002年8月,美国University of Illinois at Urbana-Champaign (UIUC)物理系和美国能源部Frederick Seitz 材料研究实验室做博士后研究。2002年8月入选中山大学“百人计划”,被聘为光电材料与技术国家重点实验室教授,材料物理与化学专业博士生导师,2004年4月――2004年6月,德国Leipzig University物理系客座教授,2004年12月入选教育部“新世纪优秀人才支持计划”。目前的研究领域:( 1)低维材料物理与化学;( 2 )纳米材料与纳米结构;(3)材料生长的热力学理论。近五年在国际重要学术刊物发表5O篇,平均SCI影响因子>2 . 7 ,应邀在国际材料科学研究领域最具有影响力的两种刊物《Progress in Materials Science》和《 Materials Science and Engineering: Report 》上面分别发表综述论文介绍我们在纳米材料物理方面的系统实验研究工作和在材料生长的热力学和动力学理论方而的系统理论研究工作.
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【期刊论文】Cubic-BN nanocrystals synthesis by pulsed laser induced liquid-solid interfacial reaction
杨国伟, J.B. Wang a, G.W. Yang a, b, *, C.Y. Zhang a, X.L. Zhong a, ZH.A. Ren a
Chemical Physics Letters 367(2003)10-14,-0001,():
-1年11月30日
Cubic boron nitride (c-BN) nanocrystals have been synthesized by pulsed laser induced liquid-solid interfacial reaction. It is shown that the diameters of the prepared quasi-spherical c-BN nanocrystals vary from 30 to 80 nm via transmission electron microscopy (TEM). The 2θ values of the X-ray diffraction (XRD) peaks of the resultant c-BN nanocrystals are 43.16°, 74.16°, 90.08° and 136.1°, respectively, corresponding to the (111), (220), (311) and (331) crystalline planes of a c-BN phase. Fourier transform infrared (FTIR) spectroscopy has also been used to characterize the structure of boron nitride. The formation of c-BN nanocrystals upon pulsed laser ablation a the liquid-solid interfaceis discussed in detail.
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【期刊论文】A Nanoscaled Thermodynamic Approach in Nucleation of CVD Diamond on Nondiamond Surfaces
杨国伟, C. Y. Zhang, C. X. Wang, Y. H. Yang, and G. W. Yang *
J. Phys. Chem. B 2004, 108, 2589-2593,-0001,():
-1年11月30日
Based on the carbon thermodynamic equilibrium phase diagram, a nanoscaled thermodynamic approach, taking the effect of nanosize-induced additional pressure on Gibbs free energy of diamond critical nuclei and phase transition probability from graphite to diamond into account, was performed to elucidate diamond nucleation on nondiamond surfaces upon chemical vapor deposition (CVD). The theoretical analysis showed that the capillary effect of the nanosize curvature of diamond critical nuclei could drive the metastable phase region of nucleation of CVD diamond into a new stable phase region in the carbon diagram. Consequently, diamond nucleation is preferable to graphite phase formation in competing growth of diamond and graphite upon CVD
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【期刊论文】Nucleation thermodynamics of quantum-dot formation in V-groove structures
杨国伟, G. W. Yang *, B. X. Liu
,-0001,():
-1年11月30日
The nucleation thermodynamics of quantum dots growth in the V-groove microscopic structure on the flat substrate by vapor phase deposition was studied, and it is proposed that the quantum dots can be formed in the designed microscopic structure by controlling the nucleation. Comparing the Gibbs free energies of the critical nuclei forming in the V-groove structure and on the flat, we found that the nuclei can form in the V-groove structure prior to the flat. Based on the V-groove structure trapping adatoms effect, the growth rate of the nuclei in the V-groove structure was calculated to be much larger than that of the nuclei on the flat upon vapor phase deposition.
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杨国伟, G. W. Yang, W. S. Lai, C. Lin, and B. X. Liu a)
Appl. Phys. Lett., Vol. 74, No.22, 31 May 1999,-0001,():
-1年11月30日
A microstructure of nanosized quasicrystals embedded in an amorphous matrix was formed in the Fe70Cu30 multilayered films upon room temperature 200keV xenon ion irradiation. The initial Fe and Cu crystalline phases in the as-deposited multilayers transformed into a unique amorphous phase at a dose of 831014 Xe1cm 22 and further irradiation, i.e., up to a dose of 531015 Xe1cm 22, induced the growth of the quasicrystals in some local areas in the amorphous matrix. High-resolution electron microscopy examination revealed that the compositions of the quasicrystals and amorphous matrix were close to Fe50Cu50 and Fe70Cu30, respectively. Apparently, the above microstructure was formed through a two-step phase transition along the increase of ion dose and the amorphous-to-quasicrystal transition was discussed in terms of the similarity in the atomic configuration between the icosahedral and amorphous short-range orders.
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杨国伟, Cheng-Xin Wang and Guo-Wei Yang a), Tie-Chen Zhang, Hong-Wu Liu, Yong-Hao Han, Ji-Feng Luo, Chun-Xiao Gao, b) and Guang-Tian Zou
Appl. Phys. Lett., Vol. 83, No.23, 8 December 2003,-0001,():
-1年11月30日
We presented the results on the fabrication and characterization of high-quality heterojunction between p-type diamond single-crystalline film and n-type cubic boron nitride (c-BN) bulk single crystal. By employing a simple surface diffusion, we prepared the n-type c-BN bulk single crystals with relatively low resistivity (1.031021 V cm). Combining p-type diamond films grown by chemical vapor deposition with n-type c-BN, we fabricated a high-quality heterojunction bipolar p-ndiode, which the turn-on voltage of the heterojunction was 0.85 V, and the current density reached to 170 A/m2 when the forward bias was applied to 3 V.
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杨国伟, Cheng-Xin Wang, Yu-Hua Yang, Qiu-Xiang Liu, and Guo-Wei Yang a), Yu-Liang Mao and Xiao-Hong Yan b)
Appl. Phys. Lett., Vol. 84, No.9, 1 March 2004,-0001,():
-1年11月30日
To clarify different phase formations of diamond nanocrystals upon pulsed-laser-induced liquid-solid interfacial reaction (PLIIR), we preformed the first-principles investigation of the total energy of cubic and hexagonal diamond. Interestingly, by a comparison of the structure stabilities of cubic and hexagonal diamond, we found that both cubic and hexagonal structures could form, simultaneously or one by one, upon those processes like as far-from equilibrium growth processes, such as PLIIR, due to the relatively small different of total energies and similar crystalline structures. Eventually, these calculations were in good agreement with the experimental results.
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杨国伟, Cheng-Xin Wang and Guo-Wei Yang a), Hong-Wu Liu, Yong-Hao Han, Ji-Feng Luo, Chun-Xiao Gao, a) and Guang-Tian Zou
,-0001,():
-1年11月30日
High-quality heterojunctions between p-type diamond single-crystalline films and highly oriented n-type ZnO films were fabricated by depositing the p-type diamond single-crystal films on the Io-type diamond single crystal using a hot filament chemical vapor deposition, and later growing a highly oriented n-type ZnO film on the p-type diamond single-crystal film by magnetron sputtering. Interestingly, anomalously high ideality factors (n>2.0) in the prepared ZnO/diamond p-n junction diode in the interim bias voltage range were measured. For this, detailed electronic characterizations of the fabricated p-n junction were conducted, and a theoretical model was proposed to clarify the much higher ideality factors of the special heterojunction diode.
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杨国伟, Cheng-Xin Wang, Yu-Hua Yang, and Guo-Wei Yang a)
APPLIED PHYSICS LETTERS VOLUME 84, NUMBER 16 19 APRIL 2004,-0001,():
-1年11月30日
A thermodynamic model in nanoscale was developed to elucidate the nucleation of the cubic boron nitrides (c-BN) synthesized in the high-pressure and high-temperature (HPHT) supercritical-fluid systems under the conditions of the low-threshold-pressure (from 2.060.1 to 3.0 Gpa) and low-temperature (1300-1500 K) Notably, taking the nanosize-induced interior pressure into account, the nucleation of c-BN could be driven to the new stable region from the metastable region in the general accepted equilibrium phase (P, T) diagram of BN proposed by Corrigan and Bundy, upon HPHT supercritical-fluid systems. The threshold pressure of the formation of c-BN was calculated based on our model, and these results are in excellent agreement with the experiment.
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杨国伟, Qiu-Xiang Liu, Cheng-Xin Wang, Yu-Hua Yang, and Guo-Wei Yang a)
Appl. Phys. Lett., Vol. 84, No.22, 31 May 2004,-0001,():
-1年11月30日
Aiming at controlling the growth of one-dimensional nanostructures inside carbon nanotubes, a growth kinetic approach was performed, with respect to the effect of nanosize induced additional pressure on growing kinetics, to theoretically elucidate the growth of one-dimensional nanostructures inside carbon nanotubes upon vapor deposition. Our analysis showed that the growth rate of one-dimensional nanostructures would go much higher once nuclei formed inside carbon nanotubes, due to the effect of surface tension induced by the nanosize curvature of carbon nanotubes. The results based on the proposed model are in good agreement with experimental data for nanowires grown inside carbon nanotubes upon vapor deposition.
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【期刊论文】Thermodynamics of Diamond Nucleation on the Nanoscale
杨国伟, C. X. Wang, Y. H. Yang, N. S. Xu, and G. W. Yang *
J. AM. CHEM. SOC. 2004, 126, 11303-11306,-0001,():
-1年11月30日
To have a clear insight into the diamond nucleation upon the hydrothermal synthesis and the reduction of carbide (HSRC), we performed the thermodynamic approach on the nanoscale to elucidate the diamond nucleation taking place in HSRC supercritical-fluid systems taking into account the capillary effect of the nanosized curvature of the diamond critical nuclei, based on the carbon thermodynamic equilibrium phase diagram. These theoretical analyses showed that the nanosize-induced interior pressure of diamond nuclei could drive the metastable phase region of the diamond nucleation in HSRC into the new stable phase region of diamond in the carbon phase diagram. Accordingly, the diamond nucleation is preferable to the graphite phase formation in the competing growth between diamond and graphite upon HSRC. Meanwhile, we predicted that 400MPa should be the threshold pressure for the diamond synthesis by HSRC in the metastable phase region of diamond, based on the proposed thermodynamic nucleation on the nanoscale.
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