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Search Results: 1 - 10 of 484 matches for " 78 "
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A Novel Fully Depleted Air AlN Silicon-on-Insulator Metal--Oxide--Semiconductor Field Effect Transistor

YANG Yuan,GAO Yong,GONG Peng-Liang,

中国物理快报 , 2008,
Abstract: A novel fully depleted air AlN silicon-on-insulator (SOI) metal--oxide--semiconductor field effect transistor (MOSFET) is presented, which can eliminate the self-heating effect and solve the problem that the off-state current of SOI MOSFETs increases and the threshold voltage characteristics become worse when employing a high thermal conductivity material as a buried layer. The simulation results reveal that the lattice temperature in normal SOI devices is 75K higher than the atmosphere temperature, while the lattice temperature is just 4K higher than the atmosphere temperature resulting in less severe self-heating effect in air AlN SOI MOSFETs and AlN SOI MOSFETs. The on-state current of air AlN SOI MOSFETs is similar to the AlN SOI structure, and improves 12.3% more than that of normal SOI MOSFETs. The off-state current of AlN SOI is 6.7 times of normal SOI MOSFETs, while the counterpart of air AlN SOI MOSFETs is lower than that of SOI MOSFETs by two orders of magnitude. The threshold voltage change of air AlN SOI MOSFETs with different drain voltage is much less than that of AlN SOI devices, when the drain voltage is biased at 0.8V, this difference is 28mV, so the threshold voltage change induced by employing high thermal conductivity material is cured.
Optical Transmittance and Band Gap of Ferroelectric BaTi2O5 Bulk Glass

Javed Ahmad,Hidetoshi Minami,Sher Alam,Jianding Yu,Yasutomo Arai,Hiromoto Uwe,

中国物理快报 , 2008,
Abstract: Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190-800nm. The fundamental absorption edge located around 340nm demonstrates the colourless and transparent character of the glass. The optical band gap of 3.32eV has been estimated. The tail of the optical absorption near the fundamental absorption edge is found to follow the Urbach rule. Our analysis of the experimental spectra supports an indirect allowed interband transition between the valence band formed by O-2p orbitals and the conduction band formed by Ti-3d orbitals.
Broadband Infrared Luminescence from Bismuth-Doped GeS2--Ga2S3 Chalcogenide Glasses

DONG Guo-Ping,XIAO Xiu-Di,REN Jin-Jun,RUAN Jian,LIU Xiao-Feng,QIU Jian-Rong,LIN Chang-Gui,TAO Hai-Zheng,ZHAO Xiu-Jian,

中国物理快报 , 2008,
Abstract: Near-infrared luminescence is observed from bismuth-doped GeS2--Ga2S3 chalcogenide glasses excited by an 808nm laser diode. The emission peak with a maximum at about 1260nm is observed in 80GeS2--20Ga2S3:0.5Biglass and it shifts toward the long wavelength with the addition of Bi gradually. The full width of half maximum (FWHM) is about 200nm. The broadband infrared luminescence of Bi-doped GeS2--Ga2S3 chalcogenide glasses may be predominantly originated from the low valence state of Bi, such as Bi+. Raman scattering is also conducted to clarify the structure of glasses. These Bi-doped GeS2--Ga2S3 chalcogenide glasses can be applied potentially in novel broadband optical fibre amplifiers and broadly tunable laser in optical communication system.
Growth Mechanism and Optimized Parameters to Synthesize Nafion-115 Nanowire Arrays with Anodic Aluminium Oxide Membranes as Templates

ZHANG Lu,PAN Cao-Feng,ZHU Jing,

中国物理快报 , 2008,
Abstract: Nafion-115 nanowire arrays are synthesized with an extrusion method using AAO membranes as templates. It is indicated that the vacuum treating of AAO templates before surface decoration plays an important role in obtaining high filling rate of the Nafion-115 nanowires in the AAO templates, while the concentration of Nafion-115 DMSO solutions does not affect the filling rate greatly. The optimized parameters to synthesize the Nafion-115 nanowire arrays are studied. The filling rate of the Nafion-115 nanowires in the AAO templates synthesized with the optimized parameters is about 95%. The growth mechanism of Nafion-115 nanowires is discussed to qualitatively explain the experimental results.
Dielectric Properties of GaN in THz Frequencies

FANG He-Nan,ZHANG Rong,LIU Bin,LU Hai,DING Jian-Ping,XIE Zi-Li,XIU Xiang-Qian,ZHENG You-Dou,XIAO Ming-Wen,ZHANG Cai-Hong,CHEN Jian,WU Pei-Heng,

中国物理快报 , 2010,
Abstract: The complex refractive indices and the dielectric function of GaN for frequencies ranging from 0.25 to 1.22THz are obtained using THz time-domain spectroscopy. The real part of the dielectric function first decreases from 0.25 to 0.42THz and then oscillates from 0.42 to 1.22THz, whereas the imaginary part of the dielectric function is oscillating within the whole range of frequency. The simple Drude model is extended to take into account the effect of defects on the dielectric function. The extended model is in agreement with the experimental data.
Effect of Rapid Thermal Annealing on the Formation of In-N Clusters in Strained InGaNAs

ZHAO Chuan-Zhen,ZHANG Rong,LIU Bin,LI Ming,XIE Zi-Li,XIU Xiang-Qian,ZHENG You-Dou,

中国物理快报 , 2010,
Abstract: A model for the effect of rapid thermal annealing on the formation of In-N clusters in strained GaInNAs is developed according to thermodynamics. In the model, the lowest annealing temperature influencing the redistribution of atoms is introduced. The average variation of energy for formation per In-N bond is obtained by fitting the experimental values. Using the present model, we calculate the average number of nearest-neighbor In atoms per N atom after annealing. The obtained results are compared with the experiment. The qualitative analysis and quantitative analysis are in good agreement with each other. The model is helpful to explain the essence of the blueshift caused by annealing.
Large Third-Order Optical Nonlinearity of Cadmium Sulphide Nanoparticles Embedded in Polymer Thin Films

WANG Cun-Xiu,FU Shi-Shu,Gu Yu-Zong,

中国物理快报 , 2009,
Abstract: A simple method for synthesis of well dispersed cadmium sulphide nanoparticles embedded in a polyethylene glycol matrix (PEG 400) in thin film form is presented. The large blue shift of the band gap energy of the CdS nanoparticles compared to the bulk semiconductors is observed via UV-vis absorption spectra. Photoluminescence spectra of CdS nanocomposite films show that the emission peaks shift towards the longer wavelength with the increase of annealing temperature. Transmission electron microscopic images as well as Raman scattering studies confirm the CdS nanometer size particle formation within the polymer matrix. The particle size is about 8 nm. Selected area electron diffraction (SAED) shows the cubic zinc blende polycrystalline rings. Third-order optical nonlinearity of the CdS nanoparticles embedded in polymer thin films is studied with the Z-scan technique under 1064 nm excitation. The results show that the CdS nanocomposite film exhibits negative nonlinear refraction index and positive absorption coefficient. The film shows large optical nonlinearity, and the magnitude of the third-order nonlinear susceptibility of the film is calculated to be 1.73×10-9 esu. The corresponding mechanism is discussed.
Vacuum Ultraviolet Excited Photoluminescence Properties of Novel Na3Y9O3(BO3)8:Tb3+ Phosphor

ZHANG Jia-Chi,WANG Yu-Hua,ZHANG Zhi-Ya,XIE Peng,LI Hui-Hui,JIANG Yan-Ping,

中国物理快报 , 2008,
Abstract: The novel vacuum ultraviolet (VUV) excited Na3Y9O3(BO3)8:Tb3+(NYOB:Tb3+) green phosphor is prepared. Strong VUV photoluminescence and high quenching concentration of Tb3+ (20wt%) are observed in NYOB:Tb3+ and the strong emission are correlated with the unique layer-type structure of NYOB. All the characteristic 4f-5d transitions of Tb3+ and the host absorption band in VUV region are identified in the excitation spectrum. Based on the results, the energy levels scheme of Tb3+ in NYOB:Tb3+ is first established. This newly developed NYOB:Tb3+ phosphor shows excellent optical properties when compared with the commercial Zn2SiO4:Mn2+ and would be a potential VUV-excited green phosphor.
Red and Near-Infrared Electroluminescences from Metal-Free Phthalocyanine

FAN Zhao-Qi,CHENG Chuan-Hui,YE Kai-Qi,YU Shu-Kun,HE Wei,XIA Dao-Cheng,GUO Zhen-Qiang,SHENG Ren-Sheng,WANG Xu,DU Xi Guang,DU Guo-Tong,

中国物理快报 , 2008,
Abstract: Organic light emitting diodes are fabricated based on metal-free phthalocyanine (H2Pc) doped into tris-(8-hydroxyquinoline) aluminium (Alq3). The device structure is ITO/NPB (30nm)/Alq3: H2Pc(30nm)/BCP(20nm)/Alq3(20 nm)/Al. In the light-emitting layers, H2Pc concentrations are varied from 0wt% to 100wt%. The emissions around 708nm and 800nm appear at low concentrations, while the emissions around 910nm and 930nm appear at high concentrations. The emissions around 708nm and 800nm are from H2Pc monomers. The emissions around 910nm and 930nm are from H2Pc aggregates. The dominant mechanism in the doped devices is direct chargetrapping.
Evolution of Luminescence with Shell's Thickness in Colloidal CdSe/CdS Core/Shell Quantum Dots

LIANG Da-Shun,SHEN Li,WANG Zhi-Bing,CUI Yi-Ping,ZHANG Jia-Yu,YE Yong-Hong,

中国物理快报 , 2008,
Abstract: We synthesize colloidal CdSe/CdS core/shell quantum dots with different shell thicknesses, and there are five samples including CdSe core dots, and CdSe/CdS core/shell dots with 1-4 CdS layers. X-ray diffraction and Raman measurements indicate that the stress in CdSe core becomes stronger with the increasing shell thickness, and the optical measurements show that when the shell becomes thicker, the photoluminescence quantum yield is enhanced, and the radiative decay is also expedited. The temperature-dependent optical spectra are measured. The relation between the microstructure and the optical properties is discussed.
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