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Wei Wang Yong Cai Yibin Zhang Hongjuan Huang Wei Huang Haiou Li Baoshun Zhang 《固体物理学:研究快报》2014,8(3):260-263
In this Letter, a GaN‐based high‐power (HP) single‐chip (SC) large‐area LED with parallel and series network structure is fabricated. The optical characteristics of the HP‐SC LED is investigated. Driven at 600 mA, the optical output power of the HP‐SC LED chip is measured to be 9.7 W, corresponding to an EQE of 26.4%, which is 19.6% lower than that of the standard small LED cell due to both the lateral light‐extraction efficiency degradation and the self‐heating effect. A statistical analysis was carried out to investigate the yield of the fabricated HP‐SC LEDs, the experimental results agree with the theoretical calculations very well, validating the feasibility of this design on the production yield for the large‐area LEDs.
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Beam alignments based on the spectrum decomposition of orbital angular momentums for acoustic-vortex communications 下载免费PDF全文
Given the enhanced channel capacity of wave chirality, acoustic communications based on the orbital angular momentum (OAM) of acoustic-vortex (AV) beams are of significant interest for underwater data transmissions. However, the stringent beam alignment is required for the coaxial arrangement of transceiver arrays to ensure the accuracy and reliability of OAM decoding. To avoid the required multiple measurements of the traditional orthogonality based algorithm, the beam alignment algorithm based on the OAM spectrum decomposition is proposed for AV communications by using simplified ring-arrays. Numerical studies of the single-OAM and OAM-multiplexed AV beams show that the error of the OAM spectrum increases with the translation distance and the deflection angle of the transceiver arrays. To achieve an ideal arrangement, two methods of the single-array translation alignment and the dual-array deflection alignment are developed based on the least standard deviation of the OAM spectrum (SD-OAM). By decreasing the SD-OAM towards zero using transceiver arrays of 16 transmitters and 16 receivers, accurate beam alignments are accomplished by multiple adjustments in three dimensions. The proposed method is also demonstrated by experimental measurements of the OAM dispersion and the SD-OAM for misaligned beams. The results demonstrate the feasibility of the rapid beam alignment based on the OAM spectrum decomposition by using simplified transceiver ring-arrays, and suggest more application potentials for acoustic communications. 相似文献
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Discrete Charge Storage Nonvolatile Memory Based on Si Nanocrystals with Nitridation Treatment 下载免费PDF全文
A nonvolatile memory device with nitrided Si nanocrystals embedded in a floating gate was fabricated. The uniform Si nanocrystals with high density (3× 10^11 cm^-2 ) were deposited on ultra-thin tunnel oxide layer (- 3 nm) and followed by a nitridation treatment in ammonia to form a thin silicon nitride layer on the surface of nanocrystals. A memory window of 2.4 V was obtained and it would be larger than 1.3 V after ten years from the extrapolated retention data. The results can be explained by the nitrogen passivation of the surface traps of Si nanoerystals, which slows the charge loss rate. 相似文献
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Observation of Coulomb Oscillations with Single Dot Characteristics in Heavy Doped Ultra Thin SOI Nanowires 下载免费PDF全文
Nanowire devices with back gate are fabricated in a heavy doped ultra thin SOI layer by electron beam lithography. Regular and periodic Coulomb oscillations with single dot behavior are observed in an appropriate back gate voltage range. The oscillation period can be determined by the back gate capacitance. The role of the back gate can control the electrical characteristics from the multi-dot junction regimes to the single dot junction regimes. These Coulomb oscillations due to single-electron tunneling are not smeared out by thermal vibration energy when the temperature is less than 40 K. 相似文献
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M. E. Sánchez A. Morán A. Escapa L. F. Calvo O. Martínez 《Journal of Thermal Analysis and Calorimetry》2007,90(1):209-215
A thermogravimetric (TG) and mass spectrometric (MS) study was carried out of the process of devolatilization of the organic
fraction of municipal solid wastes (OFMSW) and polyethylene terephthalate (PET). This involved an analysis of the heating
profiles in an inert atmosphere for each of these residues separately and for a mixture made up of half of each by mass. The
fit between the experimental and calculated values was checked by means of the least squares method. No interaction at all
was observed between the two types of waste when the fit between the experimental and theoretical figures was checked, in
the light of the low values obtained from the objective function showing fit. The study of mass spectrometry shows major emissions
of energy-producing gases although fewer pollutants are emitted. 相似文献
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Fabrication of 160-nm T-gate metamorphic AlInAs/GaInAs HEMTs on GaAs substrates by metal organic chemical vapour deposition 下载免费PDF全文
The fabrication and performance of 160-nm gate-length metamorphic AlInAs/GaInAs high electron mobility tran-sistors (mHEMTs) grown on GaAs substrate by metal organic chemical vapour deposition (MOCVD) are reported. By using a novel combined optical and e-beam photolithography technology, submicron mHEMTs devices have been achieved. The devices exhibit good DC and RF performance. The maximum current density was 817 mA/mm and the maximum transconductance was 828 mS/mm. The non-alloyed Ohmic contact resistance Rc was as low as 0.02 Ω- mm. The unity current gain cut-off frequency (fT) and the maximum oscillation frequency (fmax) were 146 GHz and 189 GHz, respectively. This device has the highest fT yet reported for a 160-nm gate-length HEMTs grown by MOCVD. The output conductance is 28.9 mS/mm, which results in a large voltage gain of 28.6. Also, an input capacitance to gate-drain feedback capacitance ratio, Cgs/Cgd, of 4.3 is obtained in the device. 相似文献
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