退火处理对ZnO纳米线紫外探测器性能的改善

通过介电泳方法定向排列了ZnO纳米线,制作了自组装有序的纳米线紫外探测器.为了适合在金叉指电极上排列,用水热方法设计生长了超长的ZnO纳米线,并通过700℃的热退火处理,使得可利用的表面缺陷增多.通过研究器件的光致发光光谱和光响应,发现光、暗电流比和响应恢复时间有显著提高,并分析了其中可能的机理.     

片上制备横向结构ZnO纳米线阵列紫外探测器件

将纳米技术与传统的微电子工艺相结合, 片上制备了横向结构氧化锌(ZnO)纳米线阵列紫外探测器件, 纳米线由水热法直接自组织横向生长于叉指电极之间, 再除去斜向的多余纳米线, 其余工艺步骤与传统工艺相同. 分别尝试了铬(Cr)和金(Au)两种金属电极的器件结构: 由于Cr电极对其上纵向生长的纳米线有抑制作用, 导致横向生长纳米线长度可到达对侧电极, 光电响应方式为受表面氧离子吸附控制的光电导效应, 光电流大但增益低, 响应速度慢, 经二次电极加固, 纳米线根部与电极金属直接形成肖特基接触, 光电响应方式变为光伏效应, 增益和速度得到了极大改善; 由于Au电极对其上纵向生长的纳米线有催化作用, 导致溶质资源的竞争, 相同时间内横向生长的纳米线不能到达对侧, 而是交叉桥接, 但却形成了紫外光诱导的纳米线间势垒结高度调控机理, 得到的器件特性为最优, 在波长为365 nm的20 mW/cm²紫外光照下, 1 V电压时暗电流为10^-9 A, 光增益可达8×10⁵, 响应时间和恢复时间分别为1.1 s和1.3 s.     

海胆状ZnO纳米线阵列的制备及其光学性能

采用一种低成本的有效方法制备出了有序排列的海胆状ZnO纳米线阵列。首先利用自组装的方法得到了单层的聚苯乙烯(PS)小球,以其为模板用水热法在小球表面生长ZnO纳米线,得到了由PS小球和ZnO纳米线构成的海胆状结构。纳米线的直径均一,长度可通过水热反应时间进行控制。利用这种方法制备的一维ZnO纳米结构在传感器、太阳能电池及光催化领域有潜在的应用价值。     

ZnO纳米线二极管发光器件制备及特性研究

运用液相法生长成ZnO纳米线薄膜，并利用肖特基型异质结的发光原理，构造成功肖特基型ZnO纳米线二极管发光器件.在大于6V直流电压驱动下，观察到近紫外波段392nm处和可见光波段525nm的发射谱带.从单向导电特性及ZnO纳米线材料的能带结构等方面探讨了该种器件的电致发光机理.     

ZnO纳米线二极管发光器件制备及特性研究

运用液相法生长成ZnO纳米线薄膜,并利用肖特基型异质结的发光原理,构造成功肖特基型ZnO纳米线二极管发光器件.在大于6V直流电压驱动下,观察到近紫外波段392nm处和可见光波段525nm的发射谱带.从单向导电特性及ZnO纳米线材料的能带结构等方面探讨了该种器件的电致发光机理. 关键词： ZnO纳米线 肖特基二极管 电致发光     

ZnO纳米线场效应管的制备及I-V特性研究

采用静电探针和原子力探针技术,将化学气相沉积工艺制备的,长度为30-200μm,直径80-750 nm的单根半导体ZnO纳米线搭接在Au,Zn,Al不同功函的金属隔离沟道两端,构建出了最基本的ZnO纳米线绝缘栅场效应管.研究了沟道类型、纳米线直径、退火温度和外加栅压对ZnO纳米线场效应管I-V特性的影响.利用半导体与金属材料的肖特基接触、欧姆接触的产生机理及电子输运理论,对结果进行了分析和讨论.     

银修饰的ZnO纳米线的发光和光响应性质

采用不同浓度的银溶液对水热方法生长的ZnO纳米线进行了银修饰,并对其形貌、光致发光和光响应特性进行了研究.实验结果表明,随着修饰用银浓度的加大,光致发光的强度减弱.对原生的和用浓度为10mmol/L的银修饰的ZnO纳米线的光响应进行了测试和比较,发现银修饰的ZnO纳米线在380 nm的响应度达4.6 mA/W,其值是未...     

单晶ZnO纳米线的合成和生长机理研究

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.     

异质结型CuO/ZnO复合纳米线的制备及光催化性能

在室温下,通过溶液法在Cu衬底上制备了CuO纳米线,然后采用溶剂热法在CuO纳米线表面生长ZnO纳米颗粒以构建CuO/ZnO复合纳米线异质结构.利用扫描电镜、透射电镜、X射线衍射仪和X射线光电子能谱分析了样品的形貌、结构和元素组成.结果显示CuO/ZnO复合纳米线由ZnO纳米颗粒和CuO纳米线组成.在模拟太阳光照射下,...     

ZnO纳米线场效应管的制备及I-V特性研究

采用静电探针和原子力探针技术,将化学气相沉积工艺制备的,长度为30—200 μm,直径80—750 nm的单根半导体ZnO纳米线搭接在Au,Zn,Al不同功函的金属隔离沟道两端,构建出了最基本的ZnO纳米线绝缘栅场效应管. 研究了沟道类型、纳米线直径、退火温度和外加栅压对ZnO纳米线场效应管I-V特性的影响. 利用半导体与金属材料的肖特基接触、欧姆接触的产生机理及电子输运理论,对结果进行了分析和讨论. 关键词： ZnO纳米线 场效应管 I-V特性')" href="#">I-V特性     

基于氧化锌纳米线的紫外发光二极管

构建了基于n-ZnO纳米线/p-Si异质结的紫外发光二极管.ZnO纳米线准阵列采用水热法生长于重掺p型Si片上.此法简易，反应温度低，易于大规模生产；其产物ZnO纳米线结晶良好，以c轴为优势取向，光激发下的紫外荧光发射很强.二极管的电学接触采用聚合物填充的In阴极或以氧化铟锡(ITO)玻璃紧压形成阴极.它们的I-V特性体现出良好的二极管性质.在正向偏置电压驱动下，构建的发光二极管可稳定发射波长在387nm的较强的近紫外光和较弱的绿光. 关键词： ZnO纳米线 异质结 电致发光 水热法     

Tuning the growth of ZnO nanowires

ZnO nanowires (NWs) with different diameters were obtained by controlling the particles of ZnO sub-layer (SL) exploring hydrothermal method; the diameter of the epitaxial NWs could be tuned from 60 to 146 nm when using SL with a thickness of 70 nm. The thickness of the SL would influence the orientation of the NWs. The top agglomerate NWs could be formed on the SL with a thickness of 10 nm, and the NWs with better orientation were obtained using SL with a thickness of 70 nm. Well aligned ZnO NWs grew perpendicular to the completely stress released SL. The diameter of the NWs was also greatly influenced by the solution concentration; thus ultra fine (diameter∼11 nm) ZnO NWs were obtained through adjusting the solution concentration to 0.001 mol/L. Through our research, we also found that the growth rate of the NWs could also be influenced by the different polarity surface of the SL. In other words, the size of the ZnO NWs could be tuned exactly under optimal conditions.     

Thermal annealing effects on the dynamic photoresponse properties of Al-doped ZnO nanowires network

In this study, UV photodetectors based on a network of aluminium-doped zinc oxide (AZO) nanowires were manufactured at a low cost; for this purpose, a fast and simple fabrication process that involved dropping nanowires dispersion solution was employed instead of the conventional e-beam lithography process that is used to manufacture single nanowire–based UV photodetectors. It was demonstrated that nanowire network–based UV photodetectors provide a much faster UV photoresponse than conventional single nanowire–based UV photodetectors. The fast UV photoresponse of the fabricated UV photodetector can be attributed to the fact that the potential barriers formed in the nanowire network junctions effectively block the flow of electrons during the process of photocurrent decay. Furthermore, the UV photoresponse under illumination by a 254 nm UV source was studied as a function of the annealing temperature of the AZO nanowires network at a bias of 5 V. The fabricated UV photodetector showed the fastest response of 2 s to UV illumination in air when the sample was annealed in air for 1 h at 300 °C.     

掺AlZnO纳米线阵列的光致发光特性研究

采用化学气相沉积方法，以金做催化剂，在Si (100)衬底上制备了掺AlZnO纳米线阵列.扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在30nm左右.X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰，说明ZnO纳米线沿c轴择优取向.掺AlZnO纳米线阵列的室温光致发光(PL)谱中出现了3个带边激子发射峰：373nm，375nm，389nm.运用激子理论推算出掺AlZnO纳米线的禁带宽度为3.343eV ，束缚激子结合能为0.156eV；纯ZnO纳米线阵列PL谱中3个带边激子发射 关键词： 光致发光 化学气相沉积(CVD) 激子 ZnO纳米线阵列     

微流控技术制备ZnO纳米线阵列及其气敏特性

利用微流控技术在微通道中制备了Zn O纳米线阵列,通过X射线衍射和扫描电子显微镜分别对纳米线的物相和表面形貌进行了表征.结果发现,合成的Zn O纳米线具有良好的c轴择优取向性和结晶度.同时,对Zn O纳米线阵列在丙酮、甲醇和乙醇气体中的气敏特性进行了研究,测试结果表明:在最佳工作温度(475?C)下,纳米线阵列对200 ppm(1 ppm=10-6)丙酮气体的最大灵敏度可达8.26,响应恢复时间分别为9和5 s;通过与传统水热法制备的Zn O纳米线的气敏性能相比较发现,基于微流控技术制备的纳米线阵列具有更高的灵敏度和更快的响应恢复速度.最后,从材料表面氧气分子得失电子的角度对Zn O纳米线气敏机理进行了讨论.     

Optical and structural properties of Eu-diffused and doped ZnO nanowires

Single crystal ZnO nanowires diffused with europium (Eu) from a solid source at 900 °C for 1 h or doped with Eu during growth have been characterized. The ZnO nanowires were grown by chemical vapor deposition on Si substrates employing Au as a catalyst. The diameter of the resulting nanowires was 200 nm with a length of 1 μm. Photoluminescence spectra excited by a He–Cd laser at room temperature showed the green luminescence at 515 nm in Eu-diffused nanowires. A small red shift of near-band-edge emission of ZnO nanowires was observed in the diffused wires, but sharp emission from Eu³ ions was not present. Transmission electron microscopy shows crystalline Eu₂O₃ formation on the diffused nanowire surface, which forms a coaxial heterostructure system. When Eu was incorporated during the nanowire growth, the sharp ⁵D_O–⁷F₂ transition of the Eu³⁺ ion at around 615 nm was observed.     

First-principles study of the electronic and optical properties of ZnO nanowires

The geometric, energetic, electronic structures and optical properties of ZnO nanowires (NWs) with hexagonal cross sections are investigated by using the first-principles calculation of plane wave ultra-soft pseudo-potential technology based on the density functional theory (DFT). The calculated results reveal that the initial Zn-O double layers merge into single layers after structural relaxations, the band gap and binding energies decrease with the increase of the ZnO nanowire size. Those properties show great dimension and size dependence. It is also found that the dielectric functions of ZnO NWs have different peaks with respect to light polarization, and the peaks of ZnO NWs exhibit a significant blueshift in comparison with those of bulk ZnO. Our results gives some reference to the thorough understanding of optical properties of ZnO, and also enables more precise monitoring and controlling during the growth of ZnO materials to be possible.     

In, Al共掺杂ZnO纳米串光电探测器的组装与研究

用化学气相沉积法合成了高密度的In, Al共掺杂ZnO纳米串, 用合成出的纳米串组装成了光电探测器. 纳米串为六角纤锌矿结构, 平均长度大约为5 μ m. 研究了光电导的机制以及光电探测器的光电特性, 包括在暗环境及紫外照射下的伏安特性、光电响应率和光电响应时间. 结果表明, 器件存在内部增益机制, 光响应时间小于0.5 s, 衰减时间约为23 s, 可用于光电探测.     

Cr掺杂ZnO纳米线的电子结构和磁性

采用自旋极化密度泛函理论系统研究了Cr掺杂ZnO纳米线的电学、磁学以及光学属性.计算结果显示,Cr原子沿[0001]方向替代ZnO纳米线中的Zn原子时体系一般呈现铁磁耦合,沿[1010]和[0110]方向替代Zn原子时体系呈现反铁磁耦合,且磁性耦合状态在费米能级附近出现了明显的自旋劈裂现象,发生了强烈的Cr 3d和O 2p杂化效应.自旋态密度计算结果显示,磁矩主要来源于Cr原子未成对3d态电子的贡献,磁矩的大小与Cr原子的电子排布有关.光学性质计算结果显示,Cr掺杂ZnO纳米线在远紫外和近紫外都具有明显的吸收峰,吸收峰发生了明显的红移.这些结果都表明Cr掺杂ZnO纳米线也许是一种很有前途的稀磁半导体材料. 关键词： ZnO 纳米线 第一性原理 磁性     

Gas sensing properties of single crystalline ZnO nanowires grown by thermal evaporation technique

The ZnO NWs were applied as effective material for the fabrication of ethanol (C₂H₅OH) and carbon monoxide (CO) gas sensor. The ZnO NWs were grown by thermal evaporation techniques on non-catalytic Si (100) substrates. The average width and length of ZnO NWs was 60 nm and 20 μm, respectively and they were single crystalline in nature. The maximum response was 51.64 at 300 °C for 1000 ppm of CO gas, while 104.23 at 400 °C for 250 ppm of ethanol gas. The response of ZnO NWs was very high for ethanol compared to the CO, whereas the recovery time for ethanol was very poor compare to CO gas. The response of ZnO NWs was about 25 times higher for ethanol compare to CO, at 400 °C for 100 ppm of each gas. The high response for ethanol is related to electron donating effect of ethanol (10e^?) which was higher than the CO gas (2e^?). The high response of ZnO NWs was attributed to large contacting surface area for electrons, oxygen, target gas molecule, and abundant channels for gas diffusion.