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陆智淼孟进王波赵治华胡安琪 《声学学报》2023,(3):515-523
针对参量阵转换效率低的问题,提出了一种通过调节声源表面声阻抗率从而提高转换效率的方法。该方法依据描述声波非线性的Kuznetsov方程,首先通过分析方程中拉格朗日密度对参量阵差频波的影响,获得了拉格朗日密度与声源表面声阻抗率之间的关系式,得出了通过调整声阻抗率可以提高参量阵转换效率的结论。随后提出了利用穿孔板改变声阻抗率的方法,并通过数值仿真验证了该方法的有效性。结果表明,通过在声源周围布置声穿孔板可以改变声阻抗率从而提高参量阵的转换效率。 相似文献
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垂直腔面发射激光器因其具有低阈值、低功耗、可实现高速调制等优势,广泛地应用于光通信和光互连等领域。寄生电容是影响激光器的调制带宽的主要因素之一。本文通过采用低k值的苯并环丁烯(BCB)平整技术有效地降低了垂直腔面发射激光器的寄生电容。详细研究了BCB平整技术的最优工艺参数,为未来高速垂直腔面发射激光器的制造技术提供参考。低k值BCB平整垂直腔面发射激光器在7 μm氧化孔径下3 dB小信号调制带宽可达15.2 GHz。 相似文献
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The mechanism for electrical conduction is investigated by the dark temperature-dependent current–voltage characteristics of Si PIN photodiodes with different photosensitive areas.The characteristic tunneling energy E_(00) can be obtained to be 1.40 me V,1.53 me V,1.74 me V,1.87 me V,and 2.01 me V,respectively,for the photodiodes with L = 0.25 mm,0.5 mm,1 mm,1.5 mm,and 2 mm by fitting the ideality factor n versus temperature curves according to the tunneling-enhanced recombination mechanism.The trap-assisted tunneling-enhanced recombination in the i-layer plays an important role in our device,which is consistent with the experimental result that area-dependent leakage current is dominant with the side length larger than 1 mm of the photosensitive area.Our results reveal that the quality of the bulk material plays an important role in the electrical conduction mechanism of the devices with the side length larger than 1 mm of the photosensitive area. 相似文献
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前言
LDO线性稳压器种类繁多,应用很普遍。随着工艺和技术的不断改进,新产品层出不穷。LDO应用电路的设计虽很简单,但要想稳定可靠的使用,还是会涉及很多问题。本文结合LDO的特点,介绍了与电路设计及选型相关的性能参数,特别针对LDO本身热损耗和稳定性问题进行深入分析,以期对此类电源的设计有更好的了解。 相似文献
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介绍了非晶铟镓锌氧化物薄膜晶体管(a-IGZO TFT)的制备,并在不同环境下进行了退火.其中,经过一次退火冷却后再进行第二次退火的器件表现出了最佳的电学性能,相比其他器件有较小的亚阈值摆幅(~1.43V/decade)和更好的磁滞稳定性.通过对比其他退火条件下的器件表现与工艺,发现在一次退火基础上增加的较短时间(30min)退火是这些显著提高的主要原因.这说明,在a-IGZO TFT进行了一次退火并冷却后,通过引入二次退火使得a-IGZO薄膜表面平整化和结构密实化,器件性能仍然有提高的空间. 相似文献
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Strontium titanate(SrTiO3),which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV,holds great promise for ultraviolet(UV)photodetection.However,the response performance of the conventional SrTiO3-based photodetectors is limited by the large relative dielectric constant of the material,which reduces the internal electric field for electron-hole pair separation to form a current collected by electrodes.Recently,graphene/semiconductor hybrid photodetectors by van-der-Waals heteroepitaxy method demonstrate ultrahigh sensitivity,which is benefit from the interface junction architecture and then prolonged lifetime of photoexcited carriers.Here,a graphene/SrTiO3 interface-based photodetector is demonstrated with an ultrahigh responsivity of 1.2×106 A/W at the wavelength of 325 nm and~2.4×104 A/W at 261 nm.The corresponding response time is in the order of~ms.Compared with graphene/GaN interface junctionbased hybrid photodetectors,~2 orders of magnitude improvement of the ultrahigh responsivity originates from a gain mechanism which correlates with the large work function difference induced long photo-carrier lifetime as well as the low background carrier density.The performance of high responsivity and fast response speed facilitates SrTiO3 material for further efforts seeking practical applications. 相似文献
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高精密时频比对是实现全社会信息化系统高精度的时空一致性和时频稳定性的关键技术,为国民经济发展的关键领域提供统一的时间保障。硅单光子探测器凭借其高探测效率、低噪声、低时间抖动、易于集成等优势,成为高精度星地时间比对系统中的关键核心芯片。文中分析了硅单光子探测器探测效率、暗计数和时间抖动之间的相互制约关系,在深入分析硅单光子探测器的最新研究进展的基础上,有效地攻克了探测效率和时间抖动之间的相互制约矛盾,研制出光敏面直径为200 μm、室温下探测效率达50%、时间抖动仅为46 ps的硅单光子探测器芯片,最后简单介绍了该芯片在星地时间比对中的应用效果。 相似文献