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Influence of the Cd/S Molar Ratio on the Optical and Structural Properties of Nanocrystalline CdS Thin Films

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Journal of Materials Science & Technology 2010年第3期26卷 193-199页

作者： M.Thambidurai N.Murugan N.Muthukumarasamy S.Agilan S.Vasantha R.Balasundaraprabhu3 department of physics Coimbatore Institute of Technology department of Mechanical Engineering Coimbatore Institute of Technology department of physics PSG College of Technology

Nanocrystalline CdS thin films have been deposited using precursors with different thiourea concentrationonto glass substrates by sol-gel spin coating *** crystalline nature of the films has been observedto be strongly dependent on thiourea concentration and annealing *** CdS films are found tobe nanocrystalline in nature with hexagonal *** grain size is found to be in the range of 7.6 to11.5 nm depending on the thiourea concentration and annealing *** high resolution transmissionelectron microscopy （HRTEM） results of the CdS films prepared using cadmium to thiourea molar ratio of0.3：0.3 indicate the formation of nanocrystalline CdS with grain size of 5 *** transform infrared （FTIR）analysis shows the absorption bands corresponding to Cd and *** optical study carried out to determinethe band gap of the nanostructured CdS thin films shows a strong blue *** band gap energy has beenobserved to lie in the range of 3.97 to 3.62 eV following closely the quantum confinement dependence ofenergy on crystallite *** dependence of band gap of the CdS films on the annealing temperature andthiourea concentration has also been *** photoluminescence （PL） spectra display two main emissionpeaks corresponding to the blue and green emissions of CdS.

关键词： Sol-gel CdS quantum dots High resolution transmission electronmicroscopy (HRTEM)

Critical entanglement and geometric phase of a two-qubit model with Dzyaloshinski-Moriya anisotropic interaction

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Chinese physics B 2010年第1期19卷 51-55页

作者：李志坚程璐温姣进 institute of Theoretical physics and department of physics Shanxi University

We consider a two-qubit system described by the Heisenberg XY model with Dzyaloshinski Moriya （DM） anisotropic interaction in a perpendicular magnetic field to investigate the relation between entanglement, geometric phase and quantum phase transition （QPT）. It is shown that the DM interaction has an effect on the critical boundary. The combination of entanglement and geometric phase may characterize QPT completely. Their jumps mean that the occurrence of QPT and inversely the QPT at the critical point at least corresponds to a jump of one of them.

关键词： entanglement geometric phase quantum phase transition

Increasing the range accuracy of three-dimensional ghost imaging ladar using optimum slicing number method

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Chinese physics B 2015年第12期24卷 319-324页

作者：杨旭张勇徐璐杨成华王强刘越豪赵远 department of physics Harbin Institute of Technology

The range accuracy of three-dimensional（3D） ghost imaging is derived. Based on the derived range accuracy equation, the relationship between the slicing number and the range accuracy is analyzed and an optimum slicing number（OSN）is determined. According to the OSN, an improved 3D ghost imaging algorithm is proposed to increase the range accuracy. Experimental results indicate that the slicing number can affect the range accuracy significantly and the highest range accuracy can be achieved if the 3D ghost imaging system works with OSN.

关键词： ghost imaging range accuracy optimum slicing number

Sputtered gold nanoparticles enhanced quantum dot light-emitting diodes

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Chinese physics B 2018年第8期27卷 19-24页

作者： Abida Perveen 张欣汤加仑韩登宝常帅邓罗根纪文宇钟海政 department of physics Beijing Institute of Technology department of Materials Science and Engineering Beijing Institute of Technology department of physics Jilin University

Surface plasmonic effects of metallic particles have been known to be an effective method to improve the perfor- mances of light emitting didoes. In this work, we report the sputtered Au nanoparticles enhanced electroluminescence in inverted quantum dot light emitting diodes （ITO/Au NPs/ZnMgO/QDs/TFB/PEDOT：PSS/A1）. By combining the time- resolved photoluminescence, transient electroluminescence, and ultraviolet photoelectron spectrometer measurements, the enhancement of the internal field enhanced exciton coupling to surface plasmons and the electron injection rate increasing with Au nanoparticles＇ incorporation can be explained. Phenomenological numerical calculations indicate that the electron mobility of the electron transport layer increases from 1.39 ×10-5 cm2/V-s to 1.91 ×10-5 cm2/V-s for Au NPs modified device. As a result, the maximum device luminescence is enhanced by 1.41 fold （from 14600 cd/cm2 to 20720 cd/cm2） and maximum current efficiency is improved by 1.29 fold （from 3.12 cd/A to 4.02 cd/A）.

关键词： gold nanoparticles plasmonic effect quantum dots light-emitting diodes

Effect of power variation on microstructure and surface morphology of HgCdTe films deposited by RF magnetron sputtering

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Journal of Semiconductors 2010年第5期31卷 35-39页

作者：王光华孔金丞李雄军邱锋李悰杨丽丽孔令德姬荣斌 Kunming institute of physics department of physics Science and Technology

Mercury cadmium telluride films were grown by the RF magnetron sputtering technique at different sputtering *** experiment,X-ray diffraction（XRD） and atomic force microscopy（AFM） have been used to characterize the microstructure of HgCdTe *** experimental results showed that when the growth power increased,the growth rate of HgCdTe films increased;when the growth power was less than 30 W,the HgCdTe film deposited by RF magnetron sputtering was amorphous;when the growth power was more than 30 W,the films exhibited polycrystalline *** deposited at different growth rates were found to have characteristically different formations and surface morphologies;as observed through AFM,the surface morphology is composed of longitudinal islands forming a maze-like pattern in the high deposition *** analysis also illustrated that a significant reduction in the areal density of large islands and characteristically smoother films was achieved using a low deposition rate.

关键词： HgCdTe films semiconductors growth rate microstructure surface morphology

Spin-valley quantum Hall phases in graphene

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Chinese physics B 2015年第12期24卷 477-482页

作者：田宏玉 department of physics Yancheng Institute of Technology

We theoretically investigate possible quantum Hall phases and corresponding edge states in graphene by taking a strong magnetic field, Zeeman splitting M, and sublattice potential △ into account but without spin–orbit interaction. It was found that for the undoped graphene either a quantum valley Hall phase or a quantum spin Hall phase emerges in the system, depending on relative magnitudes of M and △. When the Fermi energy deviates from the Dirac point, the quantum spin-valley Hall phase appears and its characteristic edge state is contributed only by one spin and one valley species. The metallic boundary states bridging different quantum Hall phases possess a half-integer quantized conductance, like e^2/2h or3e^2/2h. The possibility of tuning different quantum Hall states with M and △ suggests possible graphene-based spintronics and valleytronics applications.

关键词： quantum Hall phases graphene magnetic field metallic boundary states

Improvement of the axial trapping effect using azimuthally polarised trapping beam

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Chinese physics B 2010年第11期19卷 698-703页

作者：李雪璁孙秀冬 department of physics Harbin Institute of Technology

A dual optical tweezers system, which consists of a doughnut mode optical tweezer （DMOT） with the azimuthally polarised trapping beam and a solid mode optical tweezer （SMOT） with the Gauss trapping beam was constructed to compare the axial trapping effect of DMOT and SMOT. The long-distance axial trapping of ST68 microbubbles （MBs） achieved by DMOT was more stable than that of SMOT. Moreover the axial trapping force measured using the viscous drag method, was depended on the diameter of the particle, the laser power, and the numerical aperture （NA） of the objective lens. The measurement of the axial trapping force and the acquisition of CCD images of trapping effect confirmed that the DMOT showed excellent axial trapping ability than SMOT. A simple and effective method is developed to improve axial trapping effect using the azimuthally polarized beam as trapping beam. This is helpful for the long-distance manipulating of particles especially polarised biological objects in axial direction.

关键词： optical tweezers azimuthally polarised beam axial trapping force ST68 microbubbles

Photochemical kinetics for holographic grating formation in phenanthrenequinone doped poly (methyl methacrylate) photopolymer

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Chinese physics B 2009年第10期18卷 4326-4332页

作者：王健孙秀冬骆素华姜永远孟庆鑫 department of physics Harbin Institute of Technology

The photochemical kinetics of phenanthrenequinone （PQ） doped poly （methyl methacrylate） photopolymer in holographic recording was studied theoretically and experimentally. The diffusion of PQ molecules during holographic recording was negligible because of its small diffusion coefficient at room temperature. A photochemical reaction kinetics model of PQ/PMMA was established. The analytical expressions for the temporal variations of transmittance and diffraction efficiency were derived. By fitting the experimental curves, some parameters related with the polymer components were obtained by the proposed model, which can be used to analyze the photochemical process and will be helpful to the optimization of material preparation.

关键词： phenanthrenequinone doped poly(methyl methacrylate) photochemical reaction

Second-harmonic generation circular dichroism spectroscopy from tripod-like chiral molecular films

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Chinese physics B 2010年第11期19卷 427-435页

作者：王晓鸥陈立安陈历学孙秀冬李俊庆李淳飞 department of physics Harbin Institute of Technology

The second-harmonic generation （SHG） circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules. Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed. Influence of ehiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied. The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics. All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system. The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.

关键词： circular dichroism three-coupled-oscillator model tripod-like structure second- harmonic generation circular dichroism