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51.
Investigation of passivation effects in AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistor by gate-drain conductance dispersion study
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This paper studies the drain current collapse of AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbAlO dielectric by applying dual-pulsed stress to the gate and drain of the device.For NbAlO MIS-HEMT,smaller current collapse is found,especially when the gate static voltage is 8 V.Through a thorough study of the gate-drain conductance dispersion,it is found that the growth of NbAlO can reduce the trap density of the AlGaN surface.Therefore,fewer traps can be filled by gate electrons,and hence the depletion effect in the channel is suppressed effectively.It is proved that the NbAlO gate dielectric can not only decrease gate leakage current but also passivate the AlGaN surface effectively,and weaken the current collapse effect accordingly. 相似文献
52.
合成了双(2-取代-3-羟基-4-吡喃酮)合铜(II)配合物, 采用元素分析、质谱、红外光谱、电子光谱、电子自旋共振谱表征了它们为平面正方型配合物, 中心离子和配体的物质的量比为1∶2. 在STZ-糖尿病小鼠模型上, 其中双(2-乙基-3-羟基-4-吡喃酮)合铜(II)在10 mg/kg的剂量下灌胃给药, 能增加血清胰岛素的合成和分泌、降低糖尿病小鼠的血糖水平, 显示出良好的抗糖尿病的作用. 该配合物毒性低, 对正常小鼠灌胃给药的半数致死量LD50是855.9 mg/kg. 相似文献
53.
54.
Chiral N-hetereocyclic carbenes were found to be efficient catalysts for the formal [2 + 2] cycloaddition reactions of alkyl(aryl)ketenes with 2-oxoaldehydes to afford beta-lactones with alpha-quaternary-beta-tertiary stereocenters in high yields with good diastereoselectivities and excellent enantioselectivities (up to 99% ee). Both alkyl(aryl)ketenes and diarylketene worked well in this reaction. 相似文献
55.
锂离子电池镍掺杂尖晶石LiMn2O4正极材料的电子结构 总被引:2,自引:0,他引:2
采用密度泛甬平面波赝势方法对LiMn2O4和LiNi0.5Mn1.5O4的几何结构进行了优化,并计算了相应的电子结构.计算的结果表明:在Li 脱嵌前后,LiMn2O4和LiNi0.5Mn1.5O4均为导体,且锂元素主要以离子形式存在于两种材料中,O2p轨道与Mn(Ni)的3d轨道形成了较强的共价键.Li 嵌入导致Mn(Ni)3d轨道的态密度峰发生移动.Ni的掺杂导致Mn(Ni)和O2p轨道的成键作用得以加强,电子在Mn(Ni)3d轨道的填充发生变化,从而提高了电池的充放电电压. 相似文献
56.
Ting-Feng Yi Jie Shu Yan-Rong Zhu An-Na Zhou Rong-Sun Zhu 《Electrochemistry communications》2009,11(1):91-94
LiMn1.4Cr0.2Ni0.4O4 and a series of Li4Ti5O12/LiMn1.4Cr0.2Ni0.4O4 composites were prepared by a solution method. XRD reveals that the LTO-coated LiMn1.4Cr0.2Ni0.4O4 samples have better crystallinity than that of pure LiMn1.4Cr0.2Ni0.4O4. SEM and EDX show that the surface of LiMn1.4Cr0.2Ni0.4O4 was successfully coated with Li4Ti5O12 particles after the surface modification treatment. Galvanostatic charge–discharge testing indicates 4 wt.% LTO-coated LiMn1.4Cr0.2Ni0.4O4 has the highest electrochemical performance among three samples, implying that surface modification is beneficial to the reversible intercalation and de-intercalation of Li+. 相似文献
57.
Hot carriers injection (HCI) tests for ultra-short channel n-MOSFET
devices were studied. The experimental data of short channel devices
(75--90\,nm), which does not fit formal degradation power law well,
will bring severe error in lifetime prediction. This phenomenon
usually happens under high drain voltage ($V_{\rm d}$) stress
condition. A new model was presented to fit the degradation curve
better. It was observed that the peak of the substrate current under
low drain voltage stress cannot be found in ultra-short channel
device. Devices with different channel lengths were studied under
different $V_{\rm d}$ stresses in order to understand the relations
between peak of substrate current ($I_{\rm sub}$) and channel
length/stress voltage. 相似文献
58.
The effects of channel length and width on the degradation of negative bias temperature instability (NBTI) are studied. With the channel length decreasing, the NBTI degradation increases. As tile channel edges have more damage and latent damage for the process reasons, the device can be divided into three parts: the gate and source overlap region, the middle channel region, and the gate and drain overlap region. When the NBTI stress is applied, the non-uniform distribution of the generated defects in the three parts will be generated due to the inhomogeneous degradation. With tile decreasing channel length, tile channel edge regions will take up a larger ratio to the middle channel region and the degradation of NBTI is enhanced. The channel width also plays an important role in the degradation of NBTI. There is an inflection point during the decreasing channel width. There are two particular factors: the lower vertical electric field effect for the thicker gate oxide thickness of the sha/low trench isolation (STI) edge and the STI mechanical stress effecting on the NBTI degradation. The former reduces and the latter intensifies the degradation. Under the mutual compromise of the both factors, when the effect of the STI mechanical stress starts to prevail over the lower vertical electric field effect with the channel width decreasing, the inflection point comes into being. 相似文献
59.
Systematical analysis of mode-locked fiber lasers using single-walled carbon nanotube saturable absorbers
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The output characteristics of the Er-doped mode-locked fiber laser using a single-walled carbon nanotube saturable absorber are investigated theoretically with a nonlinear Schrtidinger equation and a saturable absorption equation using realistic parameters. Stable self-starting mode-locking pulses are achieved under net normal, net zero, and net anomalous cavity group velocity dispersion (GVD) respectively. A spectrum with a flat top is obtained from the net normal cavity GVD laser while a spectrum with Kelly side-bands is obtained from the net anomalous cavity GVD laser. The characteristics of the pulse duration changing with cavity GVD and modulation depth of the single-walled carbon nanotubes are discussed. The characteristics of the mode-locking pulses from net normal, net zero, and net anomalous cavity GVD mode-locked fiber lasers are compared. These systematical results are useful for designing mode-locked fiber lasers with saturable absorbers made by different kinds of carbon nano-materials. 相似文献
60.
Lithium ion batteries have become attractive for portable devices due to their higher energy density compared to other systems. With a growing interest to develop rechargeable batteries for electric vehicles, lithium iron phosphate (LiFePO4) is considered to replace the currently used LiCoO2 cathodes in lithium ion cells. LiFePO4 is a technically important cathode material for new-generation power lithium ion battery applications because of its abundance in raw materials, environmental friendliness, perfect cycling performance, and safety characteristics. However, the commercial use of LiFePO4 cathode material has been hindered to date by their low electronic conductivity. This review highlights the recent progress in improving and understanding the electrochemical performance like the rate ability and cycling performance of LiFePO4 cathode. This review sums up some important researches related to LiFePO4 cathode material, including doping and coating on surface. Doping elements with coating conductive film is an effective way to improve its rate ability. 相似文献