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| Record 1 of 20 |
| Author(s): Liang, JR (Liang Ji-ran); Hu, M (Hu Ming); Wang, XD (Wang Xiao-dong); Li, GK (Li Gui-ke); Kan, Q (Kan Qiang); Ji, A (Ji An); Yang, FH (Yang Fu-hua); Liu, J (Liu Jian); Wu, NJ (Wu Nan-jian); Chen, HD (Chen Hong-da) |
| Title: Electrical and Optical Phase Transition Properties of Nano Vanadium Dioxide Thin Films |
| Source: SPECTROSCOPY AND SPECTRAL ANALYSIS, 30 (4): 1002-1007 APR 2010 |
| Abstract: Nano-vanadium dioxide thin films were prepared through thermal annealing vanadium oxide thin films deposited by dual ion beam sputtering. The nano-vanadium dioxide thin films changed its state from semiconductor phase to metal phase through heating by homemade system. Four point probe method and Fourier transform infrared spectrum technology were employed to measure and anaylze the electrical and optical semiconductor-to-metal phase transition properties of nano-vanadium dioxide thin films, respectively. The results show that there is an obvious discrepancy between the semiconductor-to-metal phase transition properties of electrical and optical phase transition. The nano-vanadium dioxide thin films' phase transiton temperature defined by electrical phase transiton property is 63 degrees C, higher than that defined by optical phase transiton property at 5 mu m, 60 degrees C; and the temperature width of electrical phase transition duration is also wider than that of optical phase transiton duration. The semiconductor-to-metal phase transiton temperature defined by optical properties increases with increasing wavelength in the region of infrared wave band, and the occuring temperature of phase transiton from semiconductor to metal also increases with wavelength increasing, but the duration temperature width of transition decreases with wavelength increasing. The phase transition properties of nano-vanadium dioxide thin film has obvious relationship with wavelength in infrared wave band. The phase transition properties can be tuned through wavelength in infrared wave band, and the semiconductor-to-metal phase transition properties of nano vanadiium dioxide thin films can be better characterized by electrical property. |
| ISSN: 1000-0593 |
| DOI: 10.3964/j.issn.1000-0593(2010)04-1002-06 |
| Record 2 of 20 |
| Author(s): Liu, DY (Liu DuanYang); Xia, JB (Xia JianBai); Chang, YC (Chang YiaChung) |
| Title: Rashba electron transport in one-dimensional quantum waveguides |
| Source: SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY, 53 (1): 16-23 JAN 2010 |
| Abstract: The properties of Rashba wave function in the planar one-dimensional waveguide are studied, and the following results are obtained. Due to the Rashba effect, the plane waves of electron with the energy E divide into two kinds of waves with the wave vectors k(1)=k(0)+k(delta) and k(2)=k(0)-k(delta), where k(delta) is proportional to the Rashba coefficient, and their spin orientations are +pi/2 (spin up) and -pi/2 (spin down) with respect to the circuit, respectively. If there is gate or ferromagnetic contact in the circuit, the Rashba wave function becomes standing wave form exp(+/- ik(delta)l)sin[k(0)(l-L)], where L is the position coordinate of the gate or contact. Unlike the electron without considering the spin, the phase of the Rashba plane or standing wave function depends on the direction angle theta of the circuit. The travel velocity of the Rashba waves with the wave vector k(1) or k(2) are the same hk(0)/m*. The boundary conditions of the Rashba wave functions at the intersection of circuits are given from the continuity of wave functions and the conservation of current density. Using the boundary conditions of Rashba wave functions we study the transmission and reflection probabilities of Rashba electron moving in several structures, and find the interference effects of the two Rashba waves with different wave vectors caused by ferromagnetic contact or the gate. Lastly we derive the general theory of multiple branches structure. The theory can be used to design various spin polarized devices. |
| ISSN: 1674-7348 |
| DOI: 10.1007/s11433-010-0112-3 |
| Record 3 of 20 |
| Author(s): Zhou, XG (Zhou XiaoGuang); Ren, LF (Ren LuFeng); Li, YT (Li YunTao); Zhang, M (Zhang Meng); Yu, YD (Yu YuDe); Yu, J (Yu Jun) |
| Title: The next-generation sequencing technology: A technology review and future perspective |
| Source: SCIENCE CHINA-LIFE SCIENCES, 53 (1): 44-57 JAN 2010 |
| Abstract: As one of the most powerful tools in biomedical research, DNA sequencing not only has been improving its productivity in an exponential growth rate but also been evolving into a new layout of technological territories toward engineering and physical disciplines over the past three decades. In this technical review, we look into technical characteristics of the next-gen sequencers and provide prospective insights into their future development and applications. We envisage that some of the emerging platforms are capable of supporting the $1000 genome and $100 genome goals if given a few years for technical maturation. We also suggest that scientists from China should play an active role in this campaign that will have profound impact on both scientific research and societal healthcare systems. |
| ISSN: 1674-7305 |
| DOI: 10.1007/s11427-010-0023-6 |
| Record 4 of 20 |
| Author(s): Li, T (Li, T.); Zhang, XH (Zhang, X. H.); Zhu, YG (Zhu, Y. G.); Huang, X (Huang, X.); Han, LF (Han, L. F.); Shang, XJ (Shang, X. J.); Ni, HQ (Ni, H. Q.); Niu, ZC (Niu, Z. C.) |
| Title: Temperature dependence of hole spin relaxation in ultrathin InAs monolayers |
| Source: PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, 42 (5): 1597-1600 MAR 2010 |
| Abstract: The temperature dependence of hole spin relaxation time in both neutral and n-doped ultrathin InAs monolayers has been investigated. It has been suggested that D'yakonov-Perel (DP) mechanism dominates the spin relaxation process at both low and high temperature regimes. The appearance of a peak in temperature dependent spin relaxation time reveals the important contribution of Coulomb scatterings between carriers to the spin kinetics at low temperature, though electron-phonon scattering becomes dominant at higher temperatures. Increased electron screening effect in the n-doped sample has been suggested to account for the shortened spin relaxation time compared with the undoped one. The results suggest that hole spins are also promising for building solid-state qubits. (C) 2009 Elsevier B.V. All rights reserved. |
| ISSN: 1386-9477 |
| DOI: 10.1016/j.physe.2009.12.050 |
| Record 5 of 20 |
| Author(s): Zhou, P (Zhou, Ping); Liu, Y (Liu, Yue); Wang, YT (Wang, Yongtian) |
| Title: Pipeline Architecture and Parallel Computation-Based Real-Time Stereovision Tracking System for Surgical Navigation |
| Source: IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, 59 (5): 1240-1250 Sp. Iss. SI MAY 2010 |
| Conference Title: 26th IEEE International Instrumentation and Measurement Technology Conference |
| Conference Date: MAY 05-07, 2009 |
| Conference Location: Singapore, SINGAPORE |
| Abstract: This paper studies the development of a real-time stereovision system to track multiple infrared markers attached to a surgical instrument. Multiple stages of pipeline in field-programmable gate array (FPGA) are developed to recognize the targets in both left and right image planes and to give each target a unique label. The pipeline architecture includes a smoothing filter, an adaptive threshold module, a connected component labeling operation, and a centroid extraction process. A parallel distortion correction method is proposed and implemented in a dual-core DSP. A suitable kinematic model is established for the moving targets, and a novel set of parallel and interactive computation mechanisms is proposed to position and track the targets, which are carried out by a cross-computation method in a dual-core DSP. The proposed tracking system can track the 3-D coordinate, velocity, and acceleration of four infrared markers with a delay of 9.18 ms. Furthermore, it is capable of tracking a maximum of 110 infrared markers without frame dropping at a frame rate of 60 f/s. The accuracy of the proposed system can reach the scale of 0.37 mm RMS along the x- and y-directions and 0.45 mm RMS along the depth direction (the depth is from 0.8 to 0.45 m). The performance of the proposed system can meet the requirements of applications such as surgical navigation, which needs high real time and accuracy capability. |
| ISSN: 0018-9456 |
| DOI: 10.1109/TIM.2010.2044074 |
| Record 6 of 20 |
| Author(s): Wang, BT (Wang, B. -T.); Zhang, P (Zhang, P.); Shi, HL (Shi, H. -L.); Sun, B (Sun, B.); Li, WD (Li, W. -D.) |
| Title: Mechanical and chemical bonding properties of ground state BeH2 |
| Source: EUROPEAN PHYSICAL JOURNAL B, 74 (3): 303-308 APR 2010 |
| Abstract: The crystal structure, mechanical properties and electronic structure of ground state BeH2 are calculated employing the first-principles methods based on the density functional theory. Our calculated structural parameters at equilibrium volume are well consistent with experimental results. Elastic constants, which well obey the mechanical stability criteria, are firstly theoretically acquired. The bulk modulus B, Shear modulus G, Young's modulus E, and Poisson's ratio upsilon are deduced from the elastic constants. The bonding nature in BeH2 is fully interpreted by combining characteristics in band structure, density of states, and charge distribution. The ionicity in the Be-H bond is mainly featured by charge transfer from Be 2s to H 1s atomic orbitals while its covalency is dominated by the hybridization of H 1s and Be 2p states. The Bader analysis of BeH2 and MgH2 are performed to describe the ionic/covalent character quantitatively and we find that about 1.61 (1.6) electrons transfer from each Be (Mg) atom to H atoms. |
| ISSN: 1434-6028 |
| DOI: 10.1140/epjb/e2010-00081-x |
| Record 7 of 20 |
| Author(s): Zhang, W (Zhang, W.); Wang, L (Wang, L.); Li, L (Li, L.); Liu, J (Liu, J.); Liu, FQ (Liu, F-Q.); Wang, Z (Wang, Z.) |
| Title: Small-divergence singlemode emitting tapered distributed-feedback quantum cascade lasers |
| Source: ELECTRONICS LETTERS, 46 (7): 528-U87 APR 1 2010 |
| Abstract: A tapered distributed feedback quantum cascade laser emitting at lambda similar to 8.1 mu m is reported. Utilising a tapered waveguide structure with a surface metal grating, the device exhibited singlemode operation over the temperature range of 100 to 214 K, with sidemode suppression ratio > 20 dB and a nearly diffraction limited far-field beam divergence angle of 5.4 degrees. |
| ISSN: 0013-5194 |
| DOI: 10.1049/el.2010.0554 |
| Record 8 of 20 |
| Author(s): Xiao, JL (Xiao, Jin-Long); Yang, YD (Yang, Yue-De); Huang, YZ (Huang, Yong-Zhen) |
| Editor(s): Piprek, J; Lee, YT |
| Title: Simulation on Gain Recovery of Quantum Dot Semiconductor Optical Amplifiers by Rate Equation |
| Source: NUSOD 2009: 9TH INTERNATIONAL CONFERENCE ON NUMERICAL SIMULATION OF OPTOELECTRONIC DEVICES, PROCEEDINGS: 63-64 2009 |
| Conference Title: 9th International Conference on Numerical Simulation of Optoelectronic Devices |
| Conference Date: SEP 14-17, 2009 |
| Conference Location: Gwangju, SOUTH KOREA |
| Conference Host: Gwangju Inst Sci & Technol |
| Abstract: The gain recoveries in quantum dot semiconductor optical amplifiers are numerically studied by rate equation models. Similar to the optical pump-probe experiment, the injection of double optical pulses is used to simulate the gain recovery of a weak continuous signal for the QD SOAs. The gain recoveries are fitted by a response function with multiple exponential terms. For the pulses duration of 10 ps, the gain recovery can be described by three exponential terms with the time constants, and for the pulse with the width of 150 fs, the gain recovery can be described by two exponential terms, the reason is that the short pulse does not consume lot of carriers. |
| ISBN: 978-1-4244-4180-8 |
| Record 9 of 20 |
| Author(s): Huang, YZ (Huang, Yong-Zhen); Yang, YD (Yang, Yue-De) |
| Editor(s): Piprek, J; Lee, YT |
| Title: Calculation of Light Delay by FDTD Technique and Pade Approximation |
| Source: NUSOD 2009: 9TH INTERNATIONAL CONFERENCE ON NUMERICAL SIMULATION OF OPTOELECTRONIC DEVICES, PROCEEDINGS: 99-100 2009 |
| Conference Title: 9th International Conference on Numerical Simulation of Optoelectronic Devices |
| Conference Date: SEP 14-17, 2009 |
| Conference Location: Gwangju, SOUTH KOREA |
| Conference Host: Gwangju Inst Sci & Technol |
| Abstract: The time delay for light transmission in a coupled microring waveguide structure is calculated from the phase shift of the transmission coefficient obtained by Pade approximation with Baker's algorithm from FDTD Output. The results show that the Pade approximation is a powerful tool for saving time in FDTD simulation. |
| ISBN: 978-1-4244-4180-8 |
| Record 10 of 20 |
| Author(s): Yan, XZ (Yan, Xiaozhou); Kuang, XF (Kuang, Xiaofei); Wu, NJ (Wu, Nanjian) |
| Book Group Author(s): IEEE |
| Title: A Smart Frequency Presetting Technique for Fast Lock-in LC-PLL Frequency Synthesizer |
| Source: ISCAS: 2009 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS, VOLS 1-5: 1525-1528 2009 |
| Conference Title: IEEE International Symposium on Circuits and Systems (ISCAS 2009) |
| Conference Date: MAY 24-27, 2009 |
| Conference Location: Taipei, TAIWAN |
| Abstract: This paper proposes a smart frequency presetting technique for fast lock-in LC-PLL frequency synthesizer. The technique accurately presets the frequency of VCO with small initial frequency error and greatly reduces the lock-in time. It can automatically compensate preset frequency variation with process and temperature. A 2.4GHz synthesizer with 1MHz reference input was implemented in 0.35 mu m CMOS process. The chip core area is 0.4mm(2). Output frequency of VCO ranges from 2390 to 2600MHz. The measured results show that the typical lock-in time is 3 mu s. The phase noise is -112dBc/Hz at 600KHz offset from center frequency. The test chip consumes current of 22mA that includes the consumption of the I/O buffers. |
| ISBN: 978-1-4244-3827-3 |
| Record 11 of 20 |
| Author(s): Zhang, QD (Zhang, Quande); Liu, FQ (Liu, Feng-Qi); Zhang, W (Zhang, Wei); Lu, QY (Lu, Quanyong); Wang, LJ (Wang, Lijun); Li, L (Li, Lu); Wang, ZG (Wang, Zhanguo) |
| Title: Thermal induced facet destructive feature of quantum cascade lasers |
| Source: APPLIED PHYSICS LETTERS, 96 (14): Art. No. 141117 APR 5 2010 |
| Abstract: We present a study on the facet damage profile of quantum cascade lasers (QCLs). Conspicuous cascade half-loop damage strips on front facet are observed when QCLs catastrophically failed. Due to the large difference on thermal conductivities between active region and the substrate, dominant heat is compulsively driven to the substrate. Abundant heat accumulation and dissipation on substrate build large temperature gradient and thermal lattice mismatch. Thermal-induced stress due to sequential mismatch leads to the occurrence of the multistep damages on front facet. Good agreement is achieved between the observed locations of damaged strips and the calculated results. |
| ISSN: 0003-6951 |
| Article Number: 141117 |
| DOI: 10.1063/1.3385159 |
| Record 12 of 20 |
| Author(s): Zhu, JJ (Zhu, Jia-Ji); Chang, K (Chang, Kai); Liu, RB (Liu, Ren-Bao); Lin, HQ (Lin, Hai-Qing) |
| Title: Electrically controllable RKKY interaction in semiconductor quantum wires |
| Source: PHYSICAL REVIEW B, 81 (11): Art. No. 113302 MAR 2010 |
| Abstract: We demonstrate in theory that it is possible to all-electrically manipulate the RKKY interaction in a quasi-one-dimensional electron gas embedded in a semiconductor heterostructure, in the presence of Rashba and Dresselhaus spin-orbit interaction. In an undoped semiconductor quantum wire where intermediate excitations are gapped, the interaction becomes the short-ranged Bloembergen-Rowland superexchange interaction. Owing to the interplay of different types of spin-orbit interaction, the interaction can be controlled to realize various spin models, e.g., isotropic and anisotropic Heisenberg-like models, Ising-like models with additional Dzyaloshinsky-Moriya terms, by tuning the external electric field and designing the crystallographic directions. Such controllable interaction forms a basis for quantum computing with localized spins and quantum matters in spin lattices. |
| ISSN: 1098-0121 |
| Article Number: 113302 |
| DOI: 10.1103/PhysRevB.81.113302 |
| Record 13 of 20 |
| Author(s): Jahn, U (Jahn, U.); Brandt, O (Brandt, O.); Luna, E (Luna, E.); Sun, X (Sun, X.); Wang, H (Wang, H.); Jiang, DS (Jiang, D. S.); Bian, LF (Bian, L. F.); Yang, H (Yang, H.) |
| Title: Carrier capture by threading dislocations in (In,Ga)N/GaN heteroepitaxial layers |
| Source: PHYSICAL REVIEW B, 81 (12): Art. No. 125314 MAR 2010 |
| Abstract: Using spatially resolved cathodoluminescence spectroscopy, we investigate the spatial luminescence distribution in a fully strained (In,Ga)N layer, in particular, its correlation with the distribution of threading dislocations (TDs). Regarding the impact of TDs on the luminescence properties, we can clearly distinguish between pure edge-type TDs and TDs with screw component. At the positions of both types of TDs, we establish nonradiative recombination sinks. The radius for carrier capture is at least four times larger for TDs with screw component as for pure edge-type TDs. The large capture radius of the former is due to a spiral-like growth mode resulting in an increase in the In content in the center of the spiral domains in comparison to their periphery. |
| ISSN: 1098-0121 |
| Article Number: 125314 |
| DOI: 10.1103/PhysRevB.81.125314 |
| Record 14 of 20 |
| Author(s): Wang, SJ (Wang, Shi-Jiang); Huang, YZ (Huang, Yong-Zhen); Yang, YD (Yang, Yue-De); Lin, JD (Lin, Jian-Dong); Che, KJ (Che, Kai-Jun); Xiao, JL (Xiao, Jin-Long); Du, Y (Du, Yun) |
| Title: Long rectangle resonator 1550 nm AlGaInAs/InP lasers |
| Source: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 27 (4): 719-724 APR 2010 |
| Abstract: 1550 nm AlGaInAs/InP long rectangle resonator lasers with three sides surrounded by SiO2 and p electrode layers are fabricated by planar technology, and room-temperature continuous-wave lasing is realized for a laser with a length of 53 mu m and a width of 2 mu m. Multiple peaks with wavelength intervals of Fabry-Perot mode intervals and mode Q factors of about 400 and a lasing mode with a Q factor over 8000 are observed from the lasing spectrum at threshold current. The numerical results of the FDTD simulation indicate that the lasing mode may be a whispering-gallery mode, which is a coupled mode of two high-order transverse modes of the waveguide. (C) 2010 Optical Society of America |
| ISSN: 0740-3224 |
| Record 15 of 20 |
| Author(s): Xu, DW (Xu, D. W.); Tong, CZ (Tong, C. Z.); Yoon, SF (Yoon, S. F.); Zhao, LJ (Zhao, L. J.); Ding, Y (Ding, Y.); Fan, WJ (Fan, W. J.) |
| Title: Self-heating effect in 1.3 mu m p-doped InAs/GaAs quantum dot vertical cavity surface emitting lasers |
| Source: JOURNAL OF APPLIED PHYSICS, 107 (6): Art. No. 063107 MAR 15 2010 |
| Abstract: The self-heating effect in 1.3 mu m p-doped InAs/GaAs quantum dot (QD) vertical cavity surface emitting lasers (VCSELs) has been investigated using a self-consistent theoretical model. Good agreement is obtained between theoretical analysis and experimental results under pulsed operation. The results show that in p-doped QD VCSELs, the output power is significantly influenced by self-heating. About 60% of output power is limited by self-heating in a device with oxide aperture of 5x6 mu m(2). This value reduces to 55% and 48%, respectively, as the oxide aperture increases to 7x8 and 15x15 mu m(2). The temperature increase in the active region and injection efficiency of the QDs are calculated and discussed based on the different oxide aperture areas and duty cycle. |
| ISSN: 0021-8979 |
| Article Number: 063107 |
| DOI: 10.1063/1.3309954 |
| Record 16 of 20 |
| Author(s): Tang, GH (Tang Guang-Hua); Xu, B (Xu Bo); Jiang, LW (Jiang Li-Wen); Kong, JX (Kong Jin-Xia); Kong, N (Kong Ning); Liang, DC (Liang De-Chun); Liang, P (Liang Ping); Ye, XL (Ye Xiao-Ling); Jin, P (Jin Peng); Liu, FQ (Liu Feng-Qi); Chen, YH (Chen Yong-Hai); Wang, ZG (Wang Zhan-Guo) |
| Title: A Photovoltaic InAs Quantum-Dot Infrared Photodetector |
| Source: CHINESE PHYSICS LETTERS, 27 (4): Art. No. 047801 APR 2010 |
| Abstract: A photovoltaic quantum dot infrared photodetector with InAs/GaAs/AlGaAs structures is reported. The detector is sensitive to normal incident light. At zero bias and 78 K, a clear spectral response in the range of 2 -7 mu m has been obtained with peaks at 3.1, 4.8 and 5.7 mu m. The bandgap energies of GaAs and Al0.2Ga0.8As at 78K are calculated and the energy diagram of the transitions in the Quantum-Dot Infrared Photodetector (QDIP) is given out. The photocurrent signals can be detected up to 110 K, which is state-of-the-art for photovoltaic QDIP. The photovoltaic effect in our detector is a result of the enhanced band asymmetry as we design in the structure. |
| ISSN: 0256-307X |
| Article Number: 047801 |
| DOI: 10.1088/0256-307X/27/4/047801 |
| Record 17 of 20 |
| Author(s): Wang, W (Wang Wei); Huang, BJ (Huang Bei-Ju); Dong, Z (Dong Zan); Liu, HJ (Liu Hai-Jun); Zhang, X (Zhang Xu); Guan, N (Guan Ning); Chen, J (Chen Jin); Guo, WL (Guo Wei-Lian); Niu, PJ (Niu Ping-Juan); Chen, HD (Chen Hong-Da) |
| Title: A Low-Voltage Silicon Light Emitting Device in Standard Salicide CMOS Technology |
| Source: CHINESE PHYSICS LETTERS, 27 (4): Art. No. 048501 APR 2010 |
| Abstract: A silicon-based field emission light emitting diode for low-voltage operation is fabricated in the standard 0.35 mu m 2P4M salicide complementary metal-oxide-semiconductor (CMOS) technology. Partially overlapping p(+) and n(+) regions with a salicide block layer are employed in this device to constitute a heavily doped p(+)-n(+) junction which has soft "knee" Zener breakdown characteristics, thus its working voltage can be reduced preferably below 5 V, and at the same time the power efficiency is improved. The spectra of this device are spread over 500nm to 1000nm with the main peak at about 722nm and an obvious red shift of the spectra peak is observed with the increasing current through the device. During the emission process, field emission rather than avalanche process plays a major role. Differences between low-voltage Zener breakdown emission and high-voltage avalanche breakdown emission performance are observed and compared. |
| ISSN: 0256-307X |
| Article Number: 048501 |
| DOI: 10.1088/0256-307X/27/4/048501 |
| Record 18 of 20 |
| Author(s): Ding, K (Ding, K.); Zeng, YP (Zeng, Y. P.); Li, YY (Li, Y. Y.); Cui, LJ (Cui, L. J.); Wang, JX (Wang, J. X.); Lu, HX (Lu, H. X.); Cong, PP (Cong, P. P.) |
| Title: Magnetoresistance in a nominally undoped InGaN thin film |
| Source: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 99 (1): 63-66 APR 2010 |
| Abstract: The magnetotransport properties of a nominally undoped InGaN thin film grown by metal-organic chemical vapor deposition were investigated. Resistivity was measured under a magnetic field up to 5 T over the temperature range of 3 to 298 K. The film exhibits a negative magnetoresistance at low temperatures. Its magnitude decreases with increasing temperature, and turns to be positive for temperatures above 100 K. The negative component was described by a model proposed by Khosla and Fischer for spin scattering of carriers in an impurity band. The positive part was attributed to the effect of Lorentz force on the carrier motion. Agreement between the model and the data is presented. |
| ISSN: 0947-8396 |
| DOI: 10.1007/s00339-009-5497-3 |
| Record 19 of 20 |
| Author(s): Liu, B (Liu, B.); Zhang, Z (Zhang, Z.); Zhang, R (Zhang, R.); Fu, DY (Fu, D. Y.); Xie, ZL (Xie, Z. L.); Lu, H (Lu, H.); Schaff, WJ (Schaff, W. J.); Song, LH (Song, L. H.); Cui, YC (Cui, Y. C.); Hua, XM (Hua, X. M.); Han, P (Han, P.); Zheng, YD (Zheng, Y. D.); Chen, YH (Chen, Y. H.); Wang, ZG (Wang, Z. G.) |
| Title: Electron concentration dependence of exciton localization and freeze-out at local potential fluctuations in InN films |
| Source: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 99 (1): 139-143 APR 2010 |
| Abstract: InN films with electron concentration ranging from n similar to 10(17) to 10(20) cm(-3) grown by metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) were investigated by variable-temperature photoluminescence and absorption measurements. The energy positions of absorption edge as well as photoluminescence peak of these InN samples with electron concentration above 10(18) cm(-3) show a distinct S-shape temperature dependence. With a model of potential fluctuations caused by electron-impurity interactions, the behavior can be quantitatively explained in terms of exciton freeze-out in local potential minima at sufficiently low temperatures, followed by thermal redistribution of the localized excitons when the band gap shrinks with increasing temperature. The exciton localization energy sigma (loc) is found to follow the n (5/12) power relation, which testifies to the observed strong localization effects in InN with high electron concentrations. |
| ISSN: 0947-8396 |
| DOI: 10.1007/s00339-010-5594-3 |
| Record 20 of 20 |
| Author(s): Li, LS (Li, Linsen); Guan, M (Guan, Min); Cao, GH (Cao, Guohua); Li, YY (Li, Yiyang); Zeng, YP (Zeng, Yiping) |
| Title: Highly efficient and stable organic light-emitting diodes employing MoO3-doped perylene-3, 4, 9, 10-tetracarboxylic dianhydride as hole injection layer |
| Source: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 99 (1): 251-254 APR 2010 |
| Abstract: We report highly efficient and stable organic light-emitting diodes (OLEDs) with MoO3-doped perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) as hole injection layer (HIL). A green OLED with structure of ITO/20 wt% MoO3: PTCDA/NPB/Alq(3)/LiF/Al shows a long lifetime of 1012 h at the initial luminance of 2000 cd/m(2), which is 1.3 times more stable than that of the device with MoO3 as HIL. The current efficiency of 4.7 cd/A and power efficiency of 3.7 lm/W at about 100 cd/m(2) have been obtained. The charge transfer complex between PTCDA and MoO3 plays a decisive role in improving the performance of OLEDs. |
| ISSN: 0947-8396 |
| DOI: 10.1007/s00339-009-5511-9 |
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