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纤锌矿结构氧化锌纳米线具有半导体性能和压电效应.用导电的原子力显微镜探针针尖去弯曲竖直生长的氧化锌纳米线,在纳米线的内部和外部分别造成压缩和拉伸,这种独特结构导致了弯曲纳米线的内外表面产生反极性的极化电荷,借助半导体性质的氧化锌纳米线和其金属尖部的肖特基势垒将电能暂时储存在氧化锌纳米线内,并可用导电的原子力显微镜探针接通这一电源,向外界输电,从而完美地实现了在纳米尺度上把机械能转化为电能.该纳米发电机的发电效率可以达到17%—30%,此项重要的科学发现将为自发电式纳米器件奠定物理基础.文章介绍了它的工作原理和潜在应用. 相似文献
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单晶ZnO纳米线的合成和生长机理研究 总被引：4，自引：0，他引：4
用化学气相输运(CVT)方法合成了直径在20～120nm呈单晶结构的ZnO纳米线.利用场发射扫描电 镜(FESEM)、高分辨透射电镜(HRTEM)以及选区电子衍射(SAED)等技术对ZnO纳米线的生长机理和结构进行 了系统研究,结果表明,纳米线的成核与Au Zn合金催化颗粒的饱和度有直接的关系,先饱和的颗粒上纳米线首 先成核.纳米线顶端合金颗粒组成的变化是导致纳米线生长终止的重要原因,大量纳米线的生长不是同时进行 的.本工作提供了支持纳米线气液固(V L S)生长机理的新实验证据,提出了氧化物纳米线的生长机理. 相似文献
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Kui Han Juanjuan WangYifeng Sheng Faliang JuXiaopeng Sheng Yuxi WuGang Tang 《Physics letters. A》2012
In this work, we study temporal evolution of multi-photon-pumped stimulated emission from ZnO nanowires. In addition to second harmonic generation, ultraviolet stimulated emission is observed in ZnO nanowires under femtosecond pulse excitation at 800 nm. Sharp emission peaks appear when excitation flux reaches a threshold of 80 mJ/cm2, which can be interpreted as lasing action in self-formed nanowire microcavities. Temporal evolution of the emission captured by Kerr shutter technique shows strong excitation-power dependence. The dynamic trace of stimulated emission exhibits a fast decay with a lifetime about 4.5 ps at intermediate excitation (∼100 mJ/cm2) and a lifetime about 2 ps at high excitation (>160 mJ/cm2). The difference in the lifetime can be attributed to different gain mechanisms related to excitonic interaction and electron-hole plasma, respectively. 相似文献
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This paper reports that a novel type of suspended ZnO nanowire field-effecttransistors (FETs) were successfully fabricated using aphotolithography process, and their electrical properties werecharacterized by I--V measurements. Single-crystalline ZnOnanowires were synthesized by a hydrothermal method, they were usedas a suspended ZnO nanowire channel of back-gate field-effecttransistors (FET). The fabricated suspended nanowire FETs showed ap-channel depletion mode, exhibited high on--off current ratio of～105. When VDS=2.5 V, the peak transconductancesof the suspended FETs were 0.396 μS, the oxide capacitance wasfound to be 1.547 fF, the pinch-off voltage VTH was about0.6 V, the electron mobility was on average 50.17 cm2/Vs. Theresistivity of the ZnO nanowire channel was estimated to be0.96× 102Ω cm at VGS = 0 V. Thesecharacteristics revealed that the suspended nanowire FET fabricatedby the photolithography process had excellent performance. Bettercontacts between the ZnO nanowire and metal electrodes could beimproved through annealing and metal deposition using a focused ionbeam. 相似文献
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Atoms under optical and magnetic trapping in a limited space at a very low temperature can lead to Bose-Einstein condensation (BEC),even in a one-dimensional (1D) optical lattice. However,can the confinment of dense excitons in a 1D semiconductor microstructure easily reach the excitonic BEC A lightly Mn(Ⅱ)-doped ZnO nanowire under a femtosecond laser pulse pump at room temperature produces single-mode lasing from coherent bipolaronic excitons,which is much like a macroscopic quantum state due to the condensation of the bipoaronic excitons if not real BEC. In this process,longitudinal biphonon binding with the exciton plays an important role. We revisit this system and propose possibility of bipolaronic exciton condensation. More studies are needed for this condensation phenomenon in 1D microcavity systems. 相似文献
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气相沉积法生长不同结构ZnO纳米线及其发光 总被引：2，自引：4，他引：2
用Zn粉、Zn/In2O3/C粉作为不同锌源,通过气相沉积法在空气或N2/O2混合气氛下生长出多种形貌的ZnO纳米线(如:四脚状、多脚状、梳子状、绒棒状,以及纳米棒、纳米丝、纳米带等多种形貌),直径约为50~1000nm,长度约为1~20μm.测量了样品的XRD谱、扫描电镜、透射电镜和选区电子衍射像,证明这些样品都是六方纤锌矿结构的ZnO单晶.四脚状样品的PL光谱显示样品存在近紫外峰(380nm)和绿峰(500nm)两个发射带,半峰全宽分别约为15,90nm,其峰值强度比其他方法(如溶液法)制得样品的峰值强.样品的尺寸对光谱强度有一定影响,但对谱峰位置并无影响.用He-Cd激光器的325nm激光对四脚状样品进行发射光谱分析,发现其近紫外激子发光大大增强而绿色缺陷发光相对较弱,近紫外的峰值位于383nm,半峰全宽约为16nm;绿峰峰值位于515nm,半峰全宽约为76nm. 相似文献
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The geometry structures,electronic structures,and magnetic properties of Zn46V2O48 nanowires are studied by density functional theory(DFT) calculations.We find that the ferromagnetic(FM) coupling is more stable for six configurations of Zn46V2O48 nanowires,and is mediated by neighboring O as evidenced from the strong hybridization of V 3d and O 2p states,exhibiting strong spin polarization.The spin polarization is found to be 100% in the Zn46V2O48 nanowires,which confirms that it is a half-metallic ferromagnet and very suitable for the injection of the spin carriers,which shows that Zn46V2O48 nanowire is one of the ideal materials to realize spin electronic devices.At the same time,the magnetic coupling mechanisms of Zn46V2O48 nanowires are analyzed with V 3d and O 2p orbitals and their magnetic moments mainly come from the contributions of the unpaired electrons of V 3d orbitals.The above results provide a theoretical basis for the preparation of 3d transition metal-doped ZnO nanowire materials. 相似文献
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本文利用第一性原理方法,研究了四种表面钝化对六角形[001]方向ZnO纳米线压电性质的影响. 研究发现,在50%H/50%Cl和50%H/50%F两种钝化中,体积效应和表面效应都起到了增强压电性的作用. 而在100%H和100%Cl的两种钝化中,表面效应被弱极化的表面电荷屏蔽,不能起到增强压电性的作用. 此外,结果还揭示了体积效应和表面效应的竞争使得实验上不能观察到ZnO纳米线压电性的直径依赖现象,并提出了利用表面钝化缩小纳米线轴向晶格常数或增大表面极化来提高压电性的方法. 相似文献
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本文利用基于密度泛函理论的第一性原理方法计算了钆(Gd)掺杂氧化锌(ZnO)纳米线的磁耦合特性. 讨论了两个Gd原子替换ZnO纳米线中不同位置Zn原子的各种可能情况. 计算发现, ZnO中掺杂的Gd原子处于相邻的位置时它们之间的相互作用是铁磁性的, 并且体系的铁磁性可以通过注入合适数目的电子来得到加强. 同时发现Gd掺杂ZnO纳米线后s-f耦合作用变得显著, 使得体系的铁磁性变得更加稳定, 这也是Gd掺杂ZnO纳米线呈现铁磁性的原因. 这些结果为实验上发现的Gd掺杂ZnO纳米线呈铁磁性提供了理论依据. 相似文献
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结合国内和国外的最新研究成果,论述了目前在NEA GaN真空面电子源研究方面的现状. 从光电发射理论、表面净化方法、阴极激活工艺、光谱响应测试以及材料本身特性等方面针对GaN真空电子源的研究取得了一定成绩:初步研究了NEA GaN电子源的光电发射机理;给出了可获得原子级清洁表面的净化方法;采用Cs或Cs/O对GaN材料进行了有效激活;测试了GaN真空电子源材料的光谱响应;探讨了影响电子源量子效率的材料特性. 指出了下一步研究需要关注的内容.关键词：NEAGaN电子源光谱响应 相似文献
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This paper studies power dependent photoluminescence spectra, thestimulated emission occurring at ultraviolet (UV) band instead of thegreen emission band of ZnO nanowires, which are prepared with achemical reduction method. The dynamics of the UV emission and greenemission is given to demonstrate the reason of stimulated emission occurring at UVband but not the green emission band under high excitation, which indicatesthat the slow decay rate of trap state makes it easy to be fully filled andsaturated, while the fast decay rate of near-band-edge exciton state makesthe UV emission dominate the radiative recombination under high excitation.The UV emission, as well as the corresponding stimulated emission, occurs incompetition with the green deep-trap emission. In addition, when pumpfluence further increases, the multiple lasing modes appear. The dependenceof these lasing modes on the pump fluence is first discussed. This diagramshould be helpful to understand and design the optical nanodevices of ZnOnanowires. 相似文献
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重离子辐照的高分子有机膜,经过适当的处理,可以作为模板制备金属和可溶性盐纳米线,此方法称为离子径迹模板法。介绍了用电化学沉积方法和过饱和溶液法制备金属纳米线和可溶性盐纳米线的基本原理和制各实例,同时还展望了离子径迹模板法制备纳米线的一些可能的应用。The polymer foils irradiated by heavy ions can be used as temptates to prepai nanowires and some inorganic salt nanowires. It is called ＂ion-track template method＂. Compared to other templates, such as AAO template and porous silicon, etched ion-track template is more convenient and flexible. The density of the pores can be easily controlled by changing the ion fluences and the diameter of the pores can be altered through changing the etching condition. The pores of the etched ion-track template are well aligned. We present some examples of preparing metallic nanowires and inorganic salt wires by electrochemical deposition and by supersaturation solution method, respectively. We also introduce some applications of nanowires prepared with ion-track template method. 相似文献
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云母模板中Cu纳米线的制备及其光学性质研究 总被引：1，自引：0，他引：1
利用快重离子辐照的单晶白云母片产生潜径迹,蚀刻得到直径在30—180 nm纳米孔道. 孔道形状依赖于蚀刻时间,蚀刻时间短得到圆柱形孔道,蚀刻时间长得到菱柱形孔道. 从而在云母模板孔道中电化学沉积得到不同直径和形状的Cu纳米线. 通过紫外可见光谱分析,发现铜纳米线的尺寸和形状影响其光学性质. 直径小于60 nm的近似为圆柱状Cu纳米线有一个明显的表面等离子体共振峰和一个微弱的次峰. 随着直径增加,菱柱状的Cu纳米线主峰有明显的红移,次峰逐渐增强. 同时利用扫描电子显微镜、X射线衍射对Cu纳米线的形貌和晶体结构特征进行了表征.关键词：Cu纳米线电化学沉积光学性质云母模板 相似文献
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Satyaprakash Sahoo G. L. Sharma Ram. S. Katiyar 《Journal of Raman spectroscopy : JRS》2012,43(1):72-75
Raman spectroscopic studies are performed to probe the stress along the length of a bent ZnO nanowire. The zone‐centre E2high optical phonon shows a systematic red shift as the junction point of the two arms of the nanowire is approached. The mechanism of the red shift is discussed on the basis of the tensile strain. From the red shift of the phonon peak position, the strain at different regions on the nanowire is estimated. Stress in the bent nanowire is also investigated using photoluminescence (PL) spectroscopy. Results of both Raman and PL study confirm that the bent nanowire is under tensile strain. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献