| Record 1 of 16 |
| Author(s): Li, J (Li, Jun); Yang, W (Yang, Wen); Chang, K (Chang, Kai) |
| Title: Spin states in InAs/AlSb/GaSb semiconductor quantum wells |
| Source: PHYSICAL REVIEW B, 80 (3): Art. No. 035303 JUL 2009 |
| Abstract: We investigate theoretically the spin states in InAs/AlSb/GaSb broken-gap quantum wells by solving the Kane model and the Poisson equation self-consistently. The spin states in InAs/AlSb/GaSb quantum wells are quite different from those obtained by the single-band Rashba model due to the electron-hole hybridization. The Rashba spin splitting of the lowest conduction subband shows an oscillating behavior. The D'yakonov-Perel' spin-relaxation time shows several peaks with increasing the Fermi wave vector. By inserting an AlSb barrier between the InAs and GaSb layers, the hybridization can be greatly reduced. Consequently, the spin orientation, the spin splitting, and the D'yakonov-Perel' spin-relaxation time can be tuned significantly by changing the thickness of the AlSb barrier. |
| ISSN: 1098-0121 |
| Article Number: 035303 |
| DOI: 10.1103/PhysRevB.80.035303 |
| Record 2 of 16 |
| Author(s): Yang, CL (Yang, Chunlei); Cui, XD (Cui, Xiaodong); Shen, SQ (Shen, Shun-Qing); Xu, ZY (Xu, Zhongying); Ge, WK (Ge, Weikun) |
| Title: Spin relaxation in submonolayer and monolayer InAs structures grown in a GaAs matrix |
| Source: PHYSICAL REVIEW B, 80 (3): Art. No. 035313 JUL 2009 |
| Abstract: Electron-spin dynamics in InAs/GaAs heterostructures consisting of a single layer of InAs (1/3-1 monolayer) embedded in (001) and (311)A GaAs matrix was studied by means of time-resolved Kerr rotation spectroscopy. The spin-relaxation time of the submonolayer InAs samples is significantly enhanced, compared with that of the monolayer InAs sample. The electron-spin-relaxation time and the effective g factor in submonolayer samples were found to be strongly dependent on the photogenerated carrier density. The contribution from both the D'yakonov-Perel' mechanism and Bir-Aronov-Pikus mechanism are discussed to interpret the temperature dependence of spin decoherence at various carrier densities. |
| ISSN: 1098-0121 |
| Article Number: 035313 |
| DOI: 10.1103/PhysRevB.80.035313 |
| Record 3 of 16 |
| Author(s): Sun, LL (Sun, Lili); Yan, FW (Yan, Fawang); Wang, JX (Wang, Junxi); Zhang, HX (Zhang, Huixiao); Zeng, YP (Zeng, Yiping); Wang, GH (Wang, Guohong); Li, JM (Li, Jinmin) |
| Title: The field emission properties of nonpolar a-plane n-type GaN films grown on nano-patterned sapphire substrates |
| Source: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 206 (7): 1501-1503 JUL 2009 |
| Abstract: Si-doped nonpolar a-plane GaN films were grown on nanopatterned sapphire substrates by a low-pressure metal organic chemical vapor deposition (MOCVD) system. The structure, morphology and field emission properties of the sample were studied by means of high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and field emission measurement. The XRD analysis shows that the sample is a nonpolar a-plane (11 (2) over bar0) GaN film. The field emission measurement shows that the nonpolar GaN films exhibit excellent field emission properties with a threshold emission field of as low as 10 V/mu m at a current density of 0.63 mu A/cm(2), and a high field emission current density of 74 mA/cm(2) at an applied field of 24 V/mu m. Moreover, the Fowler-Nordheirn plot of the sample fits a near linear relation. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
| ISSN: 1862-6300 |
| DOI: 10.1002/pssa.200925029 |
| Record 4 of 16 |
| Author(s): Zhou, B (Zhou, Bi); Pan, SW (Pan, Shuwan); Chen, SY (Chen, Songyan); Li, C (Li, Cheng); Lai, HK (Lai, Hongkai); Yu, JZ (Yu, Jinzhong); Zhu, XF (Zhu, Xianfang) |
| Title: Photoluminescence from heterogeneous SiGe/Si nanostructures prepared via a two-step approach strategy |
| Source: JOURNAL OF LUMINESCENCE, 129 (9): 1073-1077 SEP 2009 |
| Abstract: A two-step approach of preparation for SiGe/Si heterogeneous nanostructures, which combined with ultra-high vacuum chemical deposition and electrochemical anodization techniques, is demonstrated. Uniformly distributed nanostructures with a quite uniform distribution of size and morphology are obtained. A strong room-temperature photoluminescence from the nanostructures was observed with a narrow full-width at half-maximum of around 110 meV. The possible origins of the two main peaks at around 1.6 and 1.8 eV have been discussed in detail. The two-step approach is proved to be a promising method to fabricate new Si-based optoelectronic materials. (C) 2009 Elsevier B.V. All rights reserved. |
| ISSN: 0022-2313 |
| DOI: 10.1016/j.jlumin.2009.04.033 |
| Record 5 of 16 |
| Author(s): Shi, HL (Shi, Hongliang); Zhang, P (Zhang, Ping); Li, SS (Li, Shu-Shen); Xia, JB (Xia, Jian-Bai) |
| Title: Magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO: First-principles calculations |
| Source: JOURNAL OF APPLIED PHYSICS, 106 (2): Art. No. 023910 JUL 15 2009 |
| Abstract: The electronic structure and magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO have been investigated using first-principles methods. We show that the magnetic coupling between Gd or Nd ions in the nearest neighbor sites is ferromagnetic. The stability of the ferromagnetic coupling between Gd ions can be enhanced by appropriate electron doping into ZnO: Gd system and the room-temperature ferromagnetism can be achieved. However, for ZnO: Nd system, the ferromagnetism between Nd ions can be enhanced by appropriate holes doping into the sample. The room-temperature ferromagnetism can also be achieved in the n-conducting ZnO: Nd sample. Our calculated results are in good agreement with the conclusions of the recent experiments. The effect of native defects (V-Zn, V-O) on the ferromagnetism is also discussed. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3176490] |
| ISSN: 0021-8979 |
| Article Number: 023910 |
| DOI: 10.1063/1.3176490 |
| Record 6 of 16 |
| Author(s): Sun, X (sun, Xian); Jiang, DS (Jiang, Desheng); Liu, WB (Liu, Wenbao); Zhu, JH (Zhu, Jihong); Wang, H (Wang, Hui); Liu, ZS (Liu, Zongshun); Zhu, JJ (Zhu, Jianjun); Wang, YT (Wang, Yutian); Zhao, DG (Zhao, Degang); Zhang, SM (Zhang, Shuming); You, LP (You, Liping); Ma, RM (Ma, Renmin); Yang, H (Yang, Hui) |
| Title: Nonpolar growth and characterization of InN overlayers on vertically oriented GaN nanorods |
| Source: JOURNAL OF APPLIED PHYSICS, 106 (2): Art. No. 026102 JUL 15 2009 |
| Abstract: Nanostructured hexagonal InN overlayers were heteroepitaxially deposited on vertically oriented c-axis GaN nanorods by metal-organic chemical vapor deposition. InN overlayers grown in radial directions are featured by a nonpolar heteroepitaxial growth mode on GaN nanorods, showing a great difference from the conventional InN growth on (0001) c-plane GaN template. The surface of InN overlayers is mainly composed of several specific facets with lower crystallographic indices. The orientation relationship between InN and GaN lattices is found to be [0001](InN) parallel to [0001](GaN) and [1100](InN)parallel to[1100](GaN). A strong photoluminescence of InN nanostructures is observed. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3177347] |
| ISSN: 0021-8979 |
| Article Number: 026102 |
| DOI: 10.1063/1.3177347 |
| Record 7 of 16 |
| Author(s): Chen, W (Chen Wei); Xing, MX (Xing Ming-Xin); Zhou, WJ (Zhou Wen-Jun); Liu, AJ (Liu An-Jin); Zheng, WH (Zheng Wan-Hua) |
| Title: High Polarization Single Mode Photonic Crystal Microlaser |
| Source: CHINESE PHYSICS LETTERS, 26 (8): Art. No. 084210 AUG 2009 |
| Abstract: Generally, dipole mode is a doubly degenerate mode. Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property. We present a structure with elongated lattice, which only supports a single y-dipole mode. With this structure we can eliminate the degeneracy, control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode. In our experiment, the polarization extinction ratio of the y-dipole mode is as high as 51:1. |
| ISSN: 0256-307X |
| Article Number: 084210 |
| Record 8 of 16 |
| Author(s): Li, T (Li Tao); Xiang, Y (Xiang Ying); Liu, YK (Liu Yi-Kun); Wang, J (Wang Jian); Yang, SL (Yang Shun-Lin) |
| Title: Transient Reorientation of a Doped Liquid Crystal System under a Short Laser Pulse |
| Source: CHINESE PHYSICS LETTERS, 26 (8): Art. No. 086108 AUG 2009 |
| Abstract: The transient optical nonlinearity of a nematic liquid crystal doped with azo-dye DR19 is examined. The optical reorientation threshold of a 25-mu m-thick planar-aligned sample of 5CB using a 50 ns pulse duration 532 nm YAG laser pulse is observed to decrease from 800 mJ/mm(2) to 0.6 mJ/mm(2) after the addition of 1 vol% azo dopant, a reduction of three orders of magnitude. When using a laser pulse duration of 10 ns, no such effect is observed. Experimental results indicate that the azo dopant molecules undergo photoisomerization from trans-isomer to cis-isomer under exposure to light, and this conformation change reorients the 5CB molecules via intermolecular coupling between guest and host. This guest-host coupling also affects the azo photoisomerization process. |
| ISSN: 0256-307X |
| Article Number: 086108 |
| Record 9 of 16 |
| Author(s): Ruan, J (Ruan Jun); Yu, TJ (Yu Tong-Jun); Jia, CY (Jia Chuan-Yu); Tao, RC (Tao Ren-Chun); Wang, ZG (Wang Zhan-Guo); Zhang, GY (Zhang Guo-Yi) |
| Title: Indium-Induced Effect on Polarized Electroluminescence from InGaN/GaN MQWs Light Emitting Diodes |
| Source: CHINESE PHYSICS LETTERS, 26 (8): Art. No. 087802 AUG 2009 |
| Abstract: Polarization-resolved edge-emitting electroluminescence (EL) studies of InGaN/GaN MQWs of wavelengths from near-UV (390 nm) to blue (468 nm) light-emitting diodes (LEDs) are performed. Although the TE mode is dominant in all the samples of InGaN/GaN MQW LEDs, an obvious difference of light polarization properties is found in the InGaN/GaN MQW LEDs with different wavelengths. The polarization degree decreases from 52.4% to 26.9% when light wavelength increases. Analyses of band structures of InGaN/GaN quantum wells and luminescence properties of quantum dots imply that quantum-dot-like behavior is the dominant reason for the low luminescence polarization degree of blue LEDs, and the high luminescence polarization degree of UV LEDs mainly comes from QW confinement and the strain effect. Therefore, indium induced carrier confinement (quantum-dot-like behavior) might play a major role in the polarization degree change of InGaN/GaN MQW LEDs from near violet to blue. |
| ISSN: 0256-307X |
| Article Number: 087802 |
| Record 10 of 16 |
| Author(s): Zhao, DG (Zhao, D. G.); Jiang, DS (Jiang, D. S.); Zhu, JJ (Zhu, J. J.); Liu, ZS (Liu, Z. S.); Wang, H (Wang, H.); Zhang, SM (Zhang, S. M.); Wang, YT (Wang, Y. T.); Yang, H (Yang, Hui) |
| Title: Role of edge dislocation and Si impurity in linking the blue luminescence and yellow luminescence in n-type GaN films |
| Source: APPLIED PHYSICS LETTERS, 95 (4): Art. No. 041901 JUL 27 2009 |
| Abstract: A close relationship is found between the blue and yellow luminescence bands in n-type GaN films, which are grown without intentional acceptor doping. The intensity ratio of blue luminescence to yellow luminescence (I-BL/I-YL) decreases with the increase in edge dislocation densities as demonstrated by the (102) full width at half maximum of x-ray diffraction. In addition, the I-BL/I-YL ratio decreases with the increase in Si doping. It is suggested that the edge dislocation and Si impurity play important roles in linking the blue and yellow luminescence. |
| ISSN: 0003-6951 |
| Article Number: 041901 |
| DOI: 10.1063/1.3187540 |
| Record 11 of 16 |
| Author(s): Zhao, HM (Zhao, H. M.); Lombez, L (Lombez, L.); Liu, BL (Liu, B. L.); Sun, BQ (Sun, B. Q.); Xue, QK (Xue, Q. K.); Chen, DM (Chen, D. M.); Marie, X (Marie, X.) |
| Title: Electron spin quantum beats and room temperature g factor in GaAsN |
| Source: APPLIED PHYSICS LETTERS, 95 (4): Art. No. 041911 JUL 27 2009 |
| Abstract: We report on the investigation of electron spin quantum beats at room temperature in GaAsN thin films by time-resolved Kerr rotation technique. The measurement of the quantum beats, which originate from the Larmor precession of electron spins in external transverse magnetic field, yields an accurate determination of the conduction electron g factor. We show that the g factor of GaAs1-xNx thin films is significantly changed by the introduction of a small nitrogen fraction. |
| ISSN: 0003-6951 |
| Article Number: 041911 |
| DOI: 10.1063/1.3186076 |
| Record 12 of 16 |
| Author(s): Liang, JR (Liang Ji-Ran); Hu, M (Hu Ming); Wang, XD (Wang Xiao-Dong); Li, GK (Li Gui-Ke); Ji, A (Ji An); Yang, FH (Yang Fu-Hua); Liu, J (Liu Jian); Wu, NJ (Wu Nan-Jian); Chen, HD (Chen Hong-Da) |
| Title: Fabrication and Infrared Optical Properties of Nano Vanadium Dioxide Thin Films |
| Source: ACTA PHYSICO-CHIMICA SINICA, 25 (8): 1523-1529 AUG 2009 |
| Abstract: Vanadium dioxide thin films were fabricated by ion beam sputtering on Si3N4/SiO2/Si after a post reductive annealing process in a nitrogen atmosphere. X-ray Diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were employed to analyze the effects of post annealing temperature on crystallinity, morphology, and composition of the vanadium oxide thin films. Transmission properties of vanadium dioxide thin films were measured by Fourier transform-infrared (FT-IR) spectroscopy. The results showed that the as-deposited vanadium oxide thin films were composed of non-crystalline V2O5 and a tetragonal rutile VO2. After annealing at 400 degrees C for 2 h, the mixed phase vanadium oxide (VOx) thin film changed its composition and structure to VO2 and had a (011) oriented monoclinic rutile structure. When increasing the temperature to 450 degrees C, nano VO2 thin films with smaller grains were obtained. FT-IR results showed that the transmission contrast factor of the nano VO2 thin film was more than 0.99 and the transmission of smaller grain nano VO2 thin film was near zero at its switched state. Nano VO2 thin film with smaller grains is an ideal material for application in optical switching devices. |
| ISSN: 1000-6818 |
| Record 13 of 16 |
| Author(s): Tan, XT (Tan, X. T.); Zheng, HZ (Zheng, H. Z.); Liu, J (Liu, J.); Zhu, H (Zhu, H.); Xu, P (Xu, P.); Li, GR (Li, G. R.); Yang, FH (Yang, F. H.) |
| Title: Transport properties in a gated heterostructure with a trapezoidal AlxGa1-xAs barrier layer |
| Source: PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, 41 (8): 1379-1381 AUG 2009 |
| Abstract: By replacing the flat (Ga1-xAlx)As barrier layer with a trapezoidal AlxGa1-xAs barrier layer, a conventional heterostructure can be operated in enhancement mode. The sheet density of two-dimensional electron gas (2DEG) in the structure can be tuned linearly from N-2D = 0.3 x 10(11) cm(-2) to N-2D = 4.3 x 10(11) cm(-2) by changing the bias on the top gate. The present scheme for gated heterostructures is easy to fabricate and does not require the use of self-alignment photolithography or the deposition of insulating layers. In addition, this scheme facilitates the initial electrical contact to 2DEG. Although, the highest electron mobility obtained for the moment is limited by the background doping level of heterostructures, the mobility should be improved substantially in the future. (C) 2009 Elsevier B.V. All rights reserved. |
| ISSN: 1386-9477 |
| DOI: 10.1016/j.physe.2009.02.020 |
| Record 14 of 16 |
| Author(s): Zhang, Q (Zhang, Q.); Wang, XQ (Wang, X. Q.); He, XW (He, X. W.); Yin, CM (Yin, C. M.); Xu, FJ (Xu, F. J.); Shen, B (Shen, B.); Chen, YH (Chen, Y. H.); Wang, ZG (Wang, Z. G.); Ishitani, Y (Ishitani, Y.); Yoshikawa, A (Yoshikawa, A.) |
| Title: Lattice polarity detection of InN by circular photogalvanic effect |
| Source: APPLIED PHYSICS LETTERS, 95 (3): Art. No. 031902 JUL 20 2009 |
| Abstract: We report an effective and nondestructive method based on circular photogalvanic effect (CPGE) to detect the lattice polarity of InN. Because of the lattice inversion between In- and N-polar InN, the energy band spin splitting is opposite for InN films with different polarities. Consequently under light irradiation with the same helicity, CPGE photocurrents in In- and N-polar layers will have opposite directions, thus the polarity can be detected. This method is demonstrated by our CPGE measurements in both n- and p-type InN films. |
| ISSN: 0003-6951 |
| Article Number: 031902 |
| DOI: 10.1063/1.3186042 |
| Record 15 of 16 |
| Author(s): Majid, A (Majid, Abdul); Sharif, R (Sharif, Rehana); Zhu, JJ (Zhu, J. J.); Ali, A (Ali, Akbar) |
| Title: Mn-AlInN: a new diluted magnetic semiconductor |
| Source: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 96 (4): 979-984 SEP 2009 |
| Abstract: Mn ions have been incorporated into MOCVD grown Al1-x In (x) N/GaN thin films by ion implantation to achieve the room temperature ferromagnetism in the samples. Magnetic characterizations revealed the presence of two ferromagnetic transitions: one has Curie points at similar to 260 K and the other above room temperature. In-diffusion of indium caused by the Mn implantation leads to the partition of AlInN epilayer into two diluted magnetic semiconductor sub-layers depending on the Mn concentration. The Curie temperature of 260 K is assigned to the layer having lower concentration, whereas T (c) above room temperature is assumed to be associated to the layer having higher Mn concentration. |
| ISSN: 0947-8396 |
| DOI: 10.1007/s00339-009-5128-z |
| Record 16 of 16 |
| Author(s): Bai, AQ (Bai An-Qi); Hu, D (Hu Di); Ding, WC (Ding Wu-Chang); Su, SJ (Su Shao-Jian); Hu, WX (Hu Wei-Xuan); Xue, CL (Xue Chun-Lai); Fan, ZC (Fan Zhong-Chao); Cheng, BW (Cheng Bu-Wen); Yu, YD (Yu Yu-De); Wang, QM (Wang Qi-Ming) |
| Title: Silicon nanopore array structure using porous anodic alumina |
| Source: ACTA PHYSICA SINICA, 58 (7): 4997-5001 JUL 2009 |
| Abstract: A free-standing, bidirectionally permeable and ultra-thin (500-1000 nm) porous anodic alumina membrane was fabricated using a two-step aluminium anodization process, which was then placed on top of a silicon film as an etching mask. The pattern was transferred to silicon using dry-etching technology, and the silicon nanopore array structure was formed. The factors which afflct the pattern transfer process are discussed. Observation of the nanopatterned sample under a scanning electron microscope shows that the structure obtained by this method is made up of uniform and highly ordered holes, which attains to 125 nm depth. The photoluminescence spectrum from the nanopatterned sample,the surface of which has been thermal-oxidized, shows that the the luminesce is evidently enhanced, the mechanism of which is based on the normally weak TO phonon assisted bandgap light-emission process, and the physical reasons that underlic the enhancement have been analyzed. The PL results do show an attractive optical characteristic, which provides a promising pathway to achieve efficient light emission from silicon. |
| ISSN: 1000-3290 |
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