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991.
S.J. Young C.H. Hsiao L.W. Ji T.P. Chen K.J. Chen 《Journal of Physics and Chemistry of Solids》2011,72(2):147-149
The authors report the fabrication of ZnO-based metal-oxide-semiconductor field effect transistors (MOSFETs) with a high quality SiO2 gate dielectric by photochemical vapor deposition (photo-CVD) on a sapphire substrate. Compared with ZnO-based metal-semiconductor FETs (MESFETs), it was found that the gate leakage current was decreased to more than two orders of magnitude by inserting the photo-CVD SiO2 gate dielectric between ZnO and gate metal. Besides, it was also found that the fabricated ZnO MOSFETs can achieve normal operation of FET, even operated at 150 °C. This could be attributed to the high quality of photo-CVD SiO2 layer. With a 2 μm gate length, the saturated Ids and maximum transconductance (Gm) were 61.1 mA/mm and 10.2 mS/mm for ZnO-based MOSFETs measured at room temperature, while 45.7 mA/mm and 7.67 mS/mm for that measured at 150 °C, respectively. 相似文献
992.
Jo JY Chen P Sichel RJ Callori SJ Sinsheimer J Dufresne EM Dawber M Evans PG 《Physical review letters》2011,107(5):055501
The nanosecond response of a PbTiO(3)/SrTiO(3) ferroelectric/dielectric superlattice to applied electric fields is closely linked to the dynamics of striped domains of the remnant polarization. The intensity of domain satellite reflections observed with time-resolved x-ray microdiffraction decays in 5-100 ns depending on the magnitude of the electric field. The piezoelectric response of the superlattice within stripe domains is strongly suppressed due to electromechanical clamping between adjacent regions of opposite polarization. Regions of the superlattice that have been switched into a uniform polarization state by the applied electric field, however, exhibit piezoelectricity during the course of the switching process. We propose a switching model different from previous models of the switching of superlattices, based instead on a spatially heterogeneous transformation between striped and uniform polarization states. 相似文献
993.
We investigate numerically the effects of higher-order space-charge field on the self-deflection of bright photovoltaic spatial solitons in two-photon photovoltaic photorefractive crystals under steady-state conditions. The expression for an induced space-charge electric field, including higher-order space-charge field terms is obtained. The dynamical evolution equation is built in which the effects that arise from these higher-order terms are considered. Numerical results indicate that bright photovoltaic solitons can bend towards both the same direction as the crystal's c-axis and the opposite direction, respectively. Specifically, self-deflection cannot occur for bright photovoltaic solitons if the strength of the photovoltaic field and the intensity of the input beam are appropriately selected. Relevant examples are provided. 相似文献
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997.
Wook Jae Yoo Kyoung Won Jang Jeong Ki Seo Ji Yeon Heo Jin Soo Moon Jae Hoon Jun Jang-Yeon Park Bongsoo Lee 《Optical Review》2011,18(1):132-138
In this study, two types of nasal-cavity-attached fiber-optic respiration sensors have been fabricated for noninvasive respiratory
monitoring. One is a silver halide optical-fiber-based respiration sensor that can measure the variations of infrared radiation
generated by the respiratory airflow from a nasal cavity. The other is a thermochromic-pigment-based fiber-optic respiration
sensor that can measure the intensity of reflected light which changes owing to color variations of the temperature-sensing
film according to the temperature difference between inspiratory and expiratory air. We have demonstrated the similarities
of the respiratory signals using the fiber-optic respiration sensors and the temperature transducer of the BIOPAC? system.
In addition, we verified that respiratory signals without the deterioration of the MR image can be obtained using the fiber-optic
respiration sensors. It is anticipated that the proposed noninvasive fiberoptic respiration sensors will be highly effective
for respiratory monitoring of a patient during MRI procedures. 相似文献
998.
This paper describes a novel fiber-coupled heterodyne interferometer using a micro-electro-mechanical system (MEMS) mirror
and an f-theta lens. In this interferometer system, the cross-polarized laser beams operating at 2 μm with the frequency difference
of 100 kHz are introduced by means of the two acousto-optic modulators (AOM). The sample with diameter of 300 mm is uniformly
scanned by the 1 mm laser beam with the help of the combined optical scanning configuration, a MEMS mirror and an f-theta
lens. The output intermediate signal from the two channels, reference channel and the measurement channel, are processed in
the 12 bit analog-to-digital (A/D) process system. Details of our interferometer scheme are discussed. 相似文献
999.
Kihong Son Haijo Jung Sang Hun Shin Hyun-Ho Lee Mi-Sook Kim Young Hoon Ji Kum Bae Kim 《Radiation measurements》2011,46(10):1117-1122
We aimed to evaluate the suitability of a glass dosimeter (GD) for high-energy photon and electron beams in experimental and clinical use, especially for radiation therapy. We examined the expanded dosimetric characteristics of GDs including dose linearity up to 500 Gy, uniformity among GD lots and for individual GDs, the angular dependence, and energy dependence of 4 therapeutic x-ray qualities. In addition, we measured the dosimetric features (dose linearity, uniformity, angular dependence, and energy dependence) of the GD for electron beams of 10 different electron energy qualities. All measurements with the exception of dose linearity for photon beam were performed in a water phantom. For high-energy photon beams, dose linearity has a linear relationship for a dose ranging from 1 to 500 Gy with the coefficient of determination; R2 of 0.998. The uniformity of each GD of dose measurements was within ±0.5% for four GD lots and within ±1.2% for 80 GDs. In terms of the effects of photon beam angle, lower absorbed doses of within 1.0% were observed between 60° and 105° than at 90°. The GD energy dependence of 4 photon beam energy qualities was within ±2.0%. On the other hand, the result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; R2 of 0.999 between 6 and 20 MeV. The uniformity of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ±1.2%. In terms of the angular dependence to electron beams, absorbed doses were within 2.0% between 60° and 105° than at 90°. In evaluation of the energy dependence of the GD at nominal electron energies between 5 and 20 MeV, we obtained responses between 1.1% and 3.5% lower than that for a cobalt-60 beam. Our results show that GDs can be used as a detector for determining doses when a high-energy photon beam is used, and that it also has considerable potential for dose measurement of high-energy electron beam. 相似文献
1000.
X.-H. Hu A.-C. Ji X.-G. Qiu W.-M. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):473-477
We first systematically study the multivortex states in mesoscopic superconductors via self-consistent Bogoliubov-de Gennes
equations. Our work focuses on how the geometrical symmetry affects
the penetration and arrangement of vortices in mesoscopic superconductors and find that the key parameter determining the
entrance of the vortex is the current density at the hot spots on the edge of sample. Through determining the spatial distribution
of hot spots, the geometrical symmetry of the superconducting sample influences the nucleation and entrance of vortices. Our
results propose one possible experimental approach to control and manipulate the quantum states of mesoscopic superconductors
with their topological geometries, and they can be easily generalized to the confined superfluids and Bose-Einstein condensates. 相似文献