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1.
Pb(Zr0.4Ti0.6)O3 film prepared by sol-gel spin coating on a Pt/Ti/SiO2/Si substrate is applied to ferroelectric capacitors with Pt or Ru as the top electrode. For the Pt/PZT/Pt and Ru/PZT/Pt ferroelectric capacitors, although with the same ferroelectric film, different top electrode materials incur different properties of PZT capacitors, such as fatigue, leakage, remanent and saturated polarization, except the similar crystal orientations of the PZT film. After 10^10 switch cycles, the remanent polarizations of the Ru/PZT/Pt and Pt/PZT/Pt capacitors decrease to 70% and 84%, respectively. The leakage current density of the latter increases obviously at positive bias after 108 switch cycles, compared with the former. Different materials for the top electrode bring different conditions at the PZT/top electrode interface. The influence of oxygen-vacancy concentration at the PZT/electrode interface and the influence of oxides of the electrode material at the PZT/electrode interface to charge injection can explain the difference of properties of the PZT capacitors with Pt or Ru as the top electrodes.  相似文献   

2.
Properties of the Ag/Ni/p-GaN structure at different temperatures are studied by Auger electron spectroscopy, scanning electron microscopy and high resolution x-ray diffraction. The effect of Ag in ohmic contact on the crystalline quality is investigated and the optimized value of annealing temperature is reported. The lowest specific contact resistance of 2.5 × 10^-4 Ωcm^2 is obtained at annealing temperature of 550^o C.  相似文献   

3.
Ramanspectroscopyisapowerfultoolthatcanbeemployedtosolvecertainuniqueproblemsinchemical,biochemical,biophysical,andbiomedical...  相似文献   

4.
A theoretical model of flatband voltage(VFB) of metal/high-k/SiO2/Si stack is proposed based on band alignment of entire gate stack, i.e., the VFBis obtained by simultaneously considering band alignments of metal/high-k, high-k/SiO2 and SiO2/Si interfaces, and their interactions. Then the VFBof TiN/HfO2/SiO2/Si stack is experimentally obtained and theoretically investigated by this model. The theoretical calculations are in good agreement with the experimental results.Furthermore, both positive VFBshift of TiN/HfO2/SiO2/Si stack and Fermi level pinning are successfully interpreted and attributed to the dielectric contact induced gap states at TiN/HfO2 and HfO2/SiO2 interfaces.  相似文献   

5.

Chronicle

Contents of the following issues of Opticheskiĭ Zhurnal (Journal of Optical Technology)  相似文献   

6.
The squeezing and higher-order squeezing properties of k orthonormalized eigenstates of the higher powers akqs(k≥3) of the annihilation operator of two-parameter deformed harmonic oscillator are investigated. It is found that the Nth-power squeezing [N=(m+1/2)k, m=0,1,2,…] can exist in the all of them when k is even.  相似文献   

7.
A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be(223.7±1.4)×10~6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be(1086.9±6.0)×10~6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be(1310.6±7.0)×106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.  相似文献   

8.
High-resolution Fourier transform infrared spectra of natural trans-ClHCCHF and of its isotopologue trans-ClHCCDF have been recorded in the region between 700 and 1150 cm−1 with the purpose to analyze the ν11 fundamental of the main species and the ν10 of its deuterated compound. Both bands, of symmetry species A″, present c-type envelope absorptions. Beside the expected features, the K structure of the P(J), Q(J), and R(J) manifolds was resolved and identified; the assignment of the rovibrational transitions was extended up to J = 92 and Ka = 13 for the trans-35ClHCCHF and up to J = 86 and Ka = 10 for trans-35ClHCCDF. More than 2900 and 2700 lines for the main and deuterated species, respectively, were analyzed by a least-squares procedure and reliable spectroscopic molecular parameters were determined for both isotopologues.  相似文献   

9.
The number of J/ψ events collected with the BES0 detector at the BEPC/ from June 12 to July 28, 2009 is determined to be (225:3±2:8)×106 using J/ψ → inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.  相似文献   

10.
In this paper, a new equivalent circuit model of GaN-based light emitting diodes (LEDs) is established. The impact of the series resistance to luminous efficacy is simulated using the MATLAB software. GaN-based LEDs with different n- contact electrode materials (LEDs with Ni/Au and LEDs with Cr/Au) are fabricated. By comparing and analyzing the results of performances, we concluded that both the series resistance and the carrier loss could affect the luminous efficacy severely. LEDs with lower series resistance have higher luminous efficacy and its efficiency droop is alleviated simultaneously. To improve luminous efficacy, the fabrication process should be optimized for lower series resistance.  相似文献   

11.
In order to achieve good high temperature laser performance, it is essential to have very deep electron wells. InGaAs system on GaAs substrate suffers from poor temperature characteristics due to the electron overflow over the rather small conduction band offset. By means of the Harrison's model, we investigate the effect of the strain compensation on band alignments of InGaAs/GaAs laser system and show that strain compensation improves the band alignments of this laser system. The use of GaAsP or InGaP barrier instead of GaAs barrier results the strain-compensated laser system having better band alignment than that of the conventionally strained InGaAs. Therefore, high temperature operation has been anticipated in these laser systems with strain compensated barriers due to better electron and hole confinement as a result of the increased band offset and a more favorable band offset ratio.  相似文献   

12.
As an effort to improve the conversion efficiency of InGaP/InGaAs/Ge triple junction solar cells, we investigated the effect of AlGaAs barrier layer on the cell performance under concentrated light condition. Three different solar cells having upper tunnel junctions (TJs) as n++-GaAs/p++-AlGaAs layers, n++-GaAs/p++-GaAs layers and n++-GaAs/p++-GaAs/p++-AlGaAs layers were prepared. Under concentrated light condition, open-circuit voltage (VOC), fill factor (FF) and conversion efficiencies were higher for the sample with an AlGaAs barrier layer than the samples without an AlGaAs barrier layer. For the sample with an AlGaAs barrier layer, external quantum efficiency was higher than other two samples. Most of all, the sample with a TJ as n++-GaAs/p++-GaAs layers showed a very poor electrical performance, which was associated with an imperfect crystalline quality of the InGaP top cell layers.  相似文献   

13.
为了改善9xx nm高功率半导体激光器的性能,对n包层和p包层的掺杂分布进行了调整,以减小激光器的内部损耗。同时为了减小有源区载流子的泄漏,在有源区和波导层之间引入了高能量带隙GaAsP。设计并制作了内部损耗为1.25 cm-1的高功率激光器。器件可靠性工作的最大输出功率为26.5 W。当输出功率为10.5 W时,最大电光功率转换效率为72.4%,斜率效率为1.16 W/A。  相似文献   

14.
The effect of the indium (In) composition of InxGa1−xN (GaN) waveguide layers on the performance of deep violet In0.082Ga0.918N/GaN double quantum well (DQW) laser diodes (LDs) emitting at 390 nm output emission wavelength has been numerically investigated. Simulation results indicated that by increasing In composition of the InxGa1−xN waveguide layers, the threshold current decreases, the slope efficiency, and differential quantum efficiency (DQE) increase, whereas the output power decreases. The increase in the In composition of the InGaN waveguide layers increases the refractive index and consequently increases the optical confinement factor (OCF) which result in the increase in the slope efficiency and DQE and the decrease in the threshold current. The decreasing movement of electron and hole carriers from the bulk waveguide layers to the active regions also causes to decrease the output power. A new LD structure with InGaN/GaN superlattice (SL) waveguide layers has been proposed to exploit the increased OCF of InGaN waveguide structures, and the enhanced electron and hole mobilities and the tunneling effect of the periodic structure of the SL structures. The results also showed that the use of InGaN/GaN SL waveguide structures effectively improves the output power, slope efficiency and DQE and decreases the threshold current of the LD compared with (In)GaN bulk waveguide structure.  相似文献   

15.
The optical properties of indirect semiconductor quantum wells (QWs), were studied in relation to their electronic states controlled by an ultrathin AlP layer. The insertion of 1 ML of AlP at the center of a 60 Å GaAsP/GaP QW drastically increased the photoluminescence (PL) intensity and the efficiency of the no-phonon (NP) transition. The NP intensity relative to its TO phonon replica was found to greatly depend on the structural parameters and decreased by decreasing the width of the AlP layer or by increasing the arsenic composition of the GaAsP QW. The comparison with numerical calculation clarified that the efficiency of the NP transition is improved when the Xz electrons rather than Xxy electrons are involved in the radiative recombination. This can be qualitatively understood that the Xz electrons are more strongly localized to the AlP layer, leading to the efficient relaxation of the selection rule. The Arrhenius behavior of the PL intensity was also studied and the quenching of the PL intensity was interpreted as being due to the thermally activated escape of carriers from the well region into the GaP barrier.  相似文献   

16.
The effect of quantum well (QW) strain on the thermal performance of InGaP/InGaAlP lasers emitting at around 635 nm is investigated theoretically. It is found that compressively-strained QWs offer superior thermal performance due to an increased barrier height for electrons, leading to a reduced electron leakage. The theoretical predictions are supported by experimental data from red-emitting laser diodes with an improved characteristic temperature T 0.  相似文献   

17.
The influences of InGaN/GaN multiple quantum wells(MQWs) and AlGaN electron-blocking layers(EBL) on the performance of GaN-based violet laser diodes are investigated. Compared with the InGaN/GaN MQWs grown at two different temperatures, the same-temperature growth of InGaN well and GaN barrier layers has a positive effect on the threshold current and slope efficiency of laser diodes, indicating that the quality of MQWs is improved. In addition, the performance of GaN laser diodes could be further improved by increasing Al content in the AlGaN EBL due to the fact that the electron leakage current could be reduced by properly increasing the barrier height of AlGaN EBL. The violet laser diode with a peak output power of 20 W is obtained.  相似文献   

18.
The effect of the laser ridge width on the performance characteristics of deep violet In0.082Ga0.918N/GaN double quantum well (DQW) laser diodes (LDs) has been numerically investigated. Simulation results indicated that threshold current of LDs is decreased and slope efficiency and differential quantum efficiency (DQE) are increased by decreasing ridge width, whereas output power is decreased. The results also showed that a decrease of more than 1 μm in the ridge width reduces the threshold current, whereas the slope efficiency, output power, and DQE are decreased. A new DQW LD structure with a strip active region has been proposed to obtain a lower current threshold and higher output power, slope efficiency, and DQE. The results showed the InGaN DQW LD with a strip DQW active region has the highest output power, slope efficiency, and DQE; it also has a lower threshold current compared with that of the original LD. The comparative study conducted for the LDs with output emission wavelengths of 390, 414 and 436 nm has also confirmed the enhancement in LD performance using the strip DQW active region structure.  相似文献   

19.
808 nm高占空比大功率半导体激光器阵列   总被引:2,自引:1,他引:1       下载免费PDF全文
 采用渐变折射率分别限制单量子阱宽波导结构,通过降低非辐射复合、有源层载流子泄露、散射和吸收损耗来提高出射效率和降低激光阈值电流,从而提高半导体激光器阵列的输出功率;同时使P面具有更高的粒子掺杂数密度,优化N面合金条件,降低半导体激光器的串联电阻,降低焦耳热,提高了半导体激光器阵列的转换效率。利用金属有机化学气相淀积技术生长GaInAsP/InGaP/AlGaAs渐变折射率分别限制单量子阱宽波导结构激光器材料,利用该材料制成半导体激光线阵列在20%高占空比的输入电流下,半导体激光器的输出峰值功率达到189.64 W(180 A),斜率效率为1.1 W/A,中心波长为805.0 nm,阈值电流为7.6 A,电光转换效率最高可达55.4%;在1%占空比的输入电流下,阵列的输出峰值功率可达324.9 W(300 A),斜率效率为1.11 W/A,阈值电流为7.8 A,电光转化效率最高达55.6%,中心波长为804.5 nm。  相似文献   

20.
The development of new photovoltaic approach to improve costs and efficiencies is focused on the new materials and new technologies. InGaP is, in this sense, a key material for solar conversion. In particular, in the solar concentration approach, this material is part of multiple junction solar cells. Its low lattice mismatch with germanium and its adequate bandgap make it very promising. This paper shows how compositional modulation can affect the InGaP emitter and the AlGaAs tunnel junctions. The influence of the growth conditions, on the compositional modulation and misfit and threading dislocations, in In0.49Ga0.51P layers is demonstrated by TEM on purposely grown single InGaP layers. High resolution electron microscopy (HREM) intensity profiles showed no elastic lattice related modulation.  相似文献   

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