表面修饰ZnO纳米线紫外光响应的增强效应

制备了基于单根ZnO纳米线的紫外光探测原型器件,并研究了聚苯乙烯硫酸钠表面修饰对器件紫外响应特性的影响.研究发现,在相同的紫外光照射条件下,表面修饰后的器件对紫外光的探测灵敏度比修饰前提高了3个数量级.I-V特性研究表明,修饰前后器件在光照时的电导没有明显变化,但修饰后器件的暗电导却下降了3个数量级.这说明通过表面修饰降低探测器的暗电导是提高紫外光探测器灵敏度的一条重要途径. 关键词： 紫外光探测器 纳米结构 ZnO 表面修饰     

ZnO纳米线紫外探测器的制备和快速响应性能的研究

一维ZnO纳米结构由于具有比表面积大、室温下具有大激子结合能等特点而受到广泛关注. 但是如何实现纳米结构的器件一直是目前研究的一个挑战. 文章通过水热方法, 在玻璃衬底上实现了ZnO纳米线横向生长, 并制备出基于ZnO纳米线的金属-半导体-金属紫外探测器. 测量结果显示器件在365 nm处探测器的响应度达到5 A/W, 并且制备的探测器在空气中对紫外光照具有快速的响应, 其上升时间约4 s, 下降时间约5 s, 这与ZnO纳米线中的氧空位吸附和脱附水分子相关.     

ZnO纳米线双绝缘层结构电致发光器件制备及特性研究

在利用液相法生长ZnO纳米线薄膜的基础上，构造成功基于ZnO纳米线双绝缘层结构的交流电致发光器件.此器件呈现出良好的阻容特性，在室温下以一定频率的交流电压驱动，可观察到近紫外波段387 nm处和可见光波段552 nm处的发射谱带.从阻容结构的导电特性及ZnO纳米线材料的能带结构等方面探讨了这种器件的电致发光机理及频率特性.     

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.     

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     

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半导体电导型X射线探测器件研究

本文制备了基于ZnO纳米线阵列和ZnO薄膜的Ag-ZnO-Ag电导型X射线探测器件,研究了它们对X射线的响应特性.薄膜器件在100 V偏置时的响应度达到0.12μC/Gy,纳米线阵列器件在50 V偏压下的响应度达到0.17μC/Gy.器件工作机理研究表明,器件的响应过程与表面氧吸附与解吸附效应有关,氧气吸附与解吸附过程使得X射线辐照下的载流子寿命大幅度增加,从而使得器件对X射线具有较高的响应度.本文研究结果表明ZnO薄膜和纳米线阵列器件在X射线剂量测量领域具有应用前景.     

超长氧化锌纳米线的制备及其气敏性能和紫外传感应用研究

采用一种无需催化剂和载气的简便碳热还原法制得长度约为100 μm、直径约为500 nm、长径比达到200的超长ZnO纳米线,讨论了Si基底位置、沉积时间以及反应物原料的量对ZnO纳米线形貌的影响。对ZnO纳米线的气敏性能进行研究,结果表明：在工作温度为350 ℃时,ZnO纳米线传感器能够很好地检测酒精气体,具有选择性好、响应恢复快的优点,且最低检测体积分数为5×10^-6。另外,通过一种简单、实用的介电泳法制得基于ZnO纳米线的紫外传感器。在365 nm紫外灯照射下,光电流增加了13%;而在254 nm紫外灯照射时,光电流则没发生变化,说明该传感器对不同波长的紫外光有一定的选择性。     

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.     

ZnO薄膜的性质对水热生长ZnO纳米线阵列的影响

用水热法在ZnO薄膜上制备了直径、密度及取向可控的ZnO纳米线阵列。ZnO薄膜是通过原子层沉积(ALD)方法制备并在不同温度下退火处理得到的,退火温度对ZnO薄膜的晶粒尺寸、结晶质量和缺陷性质有很大的影响。而ZnO薄膜的性质对随后生长的ZnO纳米线的直径、密度及取向能起到调节控制的作用。通过扫描电子显微镜(SEM)、X射线衍射(XRD)仪和光致发光(PL)测试对ZnO薄膜和ZnO纳米线进行了表征。最后得到的垂直取向的ZnO纳米线阵列适合在发光二极管和太阳能电池等领域使用。     

Fabrication of Co-doped ZnO nanowires and their temperature-dependent ultraviolet emission properties

Co-doped ZnO nanowires have been fabricated through a high temperature vapor–solid deposition process. The temperature-dependent ultraviolet emission properties of Co-doped ZnO nanowires under 10–300 K were reported. The results show that there are multipeak emissions situated at the ultraviolet region. The investigation of the excitonic transition in Co-doped ZnO nanowires shows that there is an intensive ultraviolet periodic emission of Co-doped ZnO nanowires under low temperature. The oscillatory structure has an energy periodicity about 70 meV. The oscillatory structure is mainly attributed to the longitudinal optical phonon replicas of the free exciton. The ultraviolet emission shows an obvious redshift with the increasing temperature.     

Structural and Magnetic Properties of Codoped ZnO based Diluted Magnetic Semiconductors

Zn1-xCoxO （x = 0.01, 0.02, 0.05, 0.10 and 0.20） diluted magnetic semiconductors are prepared by the sol-gel method. The structural and magnetic properties of the samples are studied using x-ray diffraction （XRD）, extended x-ray absorption fine structure （EXAFS） and superconducting quantum interference device （SQUID）. The XRD patterns does not show any signal of precipitates that are different from wurtzite type ZnO when Co content is lower than x = 0.10. An EXAFS technique for the Co K-edge has been employed to probe the local structures around Co atoms doped in ZnO powders by fluorescence mode. The simulation results for the first shell EXAFS signals indicate that Zn sites can be substituted by Co atoms when Co content is lower than x = 0.05. The SQUID results show that the samples （x 〈 0.05） exhibit clear hysteresis loops at 300K, and magnetization versus temperature from 5 K to 350K at H = 100 Oe for the sample x = 0.02 shows that the samples have ferromagnetism above room temperature. A double-exchange mechanism is proposed to explain the ferromagnetic properties of the samples.     

聚苯胺/ZnO纳米线薄膜材料作为发光层的柔性光电器件 及其发光机理

综合氧化锌纳米线(ZnO NWs)的光学活性与聚苯胺(PANI)的空穴传输特性,设计并制备了一种聚合物/ZnO纳米线电致发光材料,并对其发光特性进行了研究。通过高分子络合软模板法,将有序的单晶ZnO NWs均匀生长在覆有铟锡氧化物(ITO)涂层的柔性聚乙烯对苯二甲酸乙二醇酯(PET)衬底上并嵌入PANI薄膜,获得了电致发光薄膜材料和有机/无机异质结实验器件ITO/(ZnO NWs-PANI)。有机/无机异质结器件电致发光可调,在相对低的开启电压下呈现室温蓝紫外发光,并且ZnO NWs表面覆盖PANI增加了蓝紫外发光的强度和稳定性;而无PANI的ZnO NWs阵列具有450 nm处的缺陷发射峰,这可能是电子从扩展态锌间隙Zn_i到价带的跃迁引起的。这些结果表明,基于PANI/ZnO纳米线的复合材料在柔性光电器件方面的应用极具潜力。     

Laser-Induced Growth Device and Optical Properties of ZnO MicrocrystalsEI北大核心CSCD

ZnO is third-generation semiconductors which can be used as the carrier of ultraviolet photoluminescence and multiresonance mode laser. In recent years, ZnO microcrystals prepared by optical vapor supersaturation precipitation (OVSP) have shown important advantages in photocatalysis, efficient multi-color light source and efficient electroluminescence. However, the high preparation cost and low production efficiency hinder the development of the large-scale device. In this work, we designed and built a set of growth devices with a working wavelength of 1 080 nm and a power of 18% (@2 500 W) laser heating. The height of the raw material rod was 6. 5 mm, and the diameter was 8 mm. The results show that the morphology, structure, and luminescence properties of the products prepared by this device are very close to those prepared by the OVSP method, and the production efficiency is greatly improved (similar to 500 %). The growth device successfully prepared acceptor-rich ZnO single crystal micro rods with complete hexagonal cross-section morphology. The diameter and length of ZnO micro rods are about 3. 8 and 10 similar to 20 mu m, respectively. Raman spectra show that the Raman peaks of ZnO micro rods are sharp, and the Raman mode at 437 cm(-1) indicates that the ZnO micro rods are hexagonal wurtzite structures with good crystallinity. By analysing the PL spectra of ZnO micro rods, it was found that the ZnO microtubes prepared by the OVSP method had a similar ultraviolet bimodal structure, indicating that there exists an abundant zinc-vacancies acceptor. In the 80 similar to 280 K range, with the increase of temperature, the fluorescence intensity of ZnO microrods appears "thermal quenching-negative thermal quenching-thermal quenching" behavior. The negative thermal quenching behavior in the range of 166 similar to 200 K is related to the intermediate state energy level (trap center) at 477 meV below the conduction band bottom, and the thermal quenching phenomenon in the range of 200 similar to 280 K is related to the non-radiative recombination center at 600 meV below the conduction band bottom. The appearance of both is related to the prepared ZnO microrod oxygen vacancy (V-o) defect. The laser growth device developed in this paper has high feasibility and practicability. This preparation method lays a technical foundation for the rapid batch growth of ZnO single crystal micro rods with rich acceptors and is also of great significance for its application in optoelectronic devices.     

低温下单根ZnO纳米带电学性质的研究

用化学气相沉积法在硅衬底上合成了宽1 μm左右、长数十微米的ZnO纳米带. 采用微栅模板法得到单根ZnO纳米带半导体器件, 由I-V特性曲线测得室温下ZnO纳米带电阻约3 MΩ, 电阻率约0.4 Ω·cm. 研究了在20–280 K温度范围内单根ZnO纳米带电阻随温度的变化. 结果表明: 在不同温度区间内电阻随温度变化趋势明显不同, 存在两种不同的输运机制. 在130–280 K较高的温度范围内, 单根ZnO纳米带电子输运机制符合热激活输运机制, 随着温度继续降低(< 130 K), 近邻跳跃传导为主导输运机制. 关键词： ZnO 纳米带 低温 输运机制     

Ultraviolet Luminescence Depending on Zn Interstitial in ZnO Polycrystalline Films

The ultraviolet emission line at 3.315eV is observed at 8K in ZnO polycrystalline films and investigated by temperature-dependent photolumineseence spectra and cathodoluminescence spatial image. The relative intensity of 3.315 eV emission line depends strongly on growth and annealing conditions. The cathodoluminescence image shows that the 3.315 eV emission localizes on the surface and ridge of ZnO grain. These results suggest that the 3.315 eV emission attributes to Zn interstitials at the grain surface and ridge. This emission is stable in the range from 8 K to 300 K and contributes to the room temperature ultraviolet band.     

纳米ZnO薄膜的激子光致发光特性

报道了纳米ZnO薄膜激子光致发光(PL)与温度的关系。首先利用低压金属有机化学气相沉积(LPMOCVD)技术生长ZnS薄膜,然后将ZnS薄膜在氧气中于800℃下热氧化2h获得纳米ZnO薄膜。X射线衍射(XRD)结果表明,纳米ZnO薄膜具有六角纤锌矿多晶结构且具有择优(002)取向。室温下观察到一束强的紫外(326eV)光致发光(PL)和很弱的深能级(DL)发射。根据激子峰的半高宽(FWHM)与温度的关系,确定了激子纵向光学声子(LO)的耦合强度(ГLO)。     

Band-edge photoluminescence in nanocrystalline ZnO:In films prepared by electrostatic spray deposition

ZnO:In films are successfully prepared by using the electrostatic spray deposition technique. X-ray diffraction indicates that the ZnO:In films have a polycrystalline hexagonal wurtzite structure with lattice parameters a=3.267 Å and c=5.209 Å. Photoluminescence properties of the films are investigated in the temperature range of 11.6-300 K, showing strong luminescence in the whole range of temperature. The temperature dependence of the photoluminescence are carried out with full profile fitting of spectra, which clearly shows that the ultraviolet (UV) emission in In-doped ZnO films at low temperature are attributed to emission of a neutral donor-bound exciton (D^°X) and recombination of donor-acceptor pairs (DAP), while the UV emission at room temperature originates from radiative transition of an electron bound on a donor to the valence band.     

Ultraviolet emission properties of ZnO film with zinc deficiency by SS CVD

A-b axis orientation ZnO film on silicon (1 0 0) substrate has been prepared by a single source chemical vapor deposition technique. X-ray photoelectron spectroscopy results revealed that the film was very close to stoichiometry but with a small amount of zinc deficiency. Temperature-dependent (10-300 K) ultraviolet photoluminescence of the film was presented. Comparing the photon energy separation of the several groups in the near band edge ultraviolet luminescence bands, as well as the variation of the relative intensities and the shift of the luminescence lines at different temperatures, free-, bound-exciton and its assisted phonon emission were observed, which corresponded to the mechanism of the ultraviolet emission properties. A strong ultraviolet emission resulting from the recombination of free-exciton was observed at 300 K photoluminescence spectrum examined in atmosphere environment. Contrasted to the relatively weak ultraviolet emission of the film in vacuum, atmosphere environment was found to be an important contribution to the strong ultraviolet emission of the film.     

ZnO量子点的制备及其在白光LED中的应用

利用湿化学方法制备合成Zn O量子点,通过改变合成条件(反应时间、反应物浓度、反应温度)对量子点的尺寸及发光性能进行调控。利用透射电子显微镜、吸收光谱、荧光光谱等表征手段,探讨了合成条件对Zn O量子点光学性质的影响,并优化出适用于构建白光LED器件的最佳合成条件。研究结果表明,在反应温度为20℃、反应时间为3 h、前驱体Zn(OAc)_2和Li OH反应浓度比为2∶1时获得的Zn O量子点较为稳定,并在紫外光激发下发出明亮的黄绿色光。在此基础上,以该Zn O量子点为有源层、p-Ga N∶Mg基片为空穴注入层、非晶Al_2O_3薄膜为电子阻挡层构造了p-i-n型异质结LED,在正向注入电流为5 m A时,获得了来自于器件的白光发射,其色坐标为(0.28,0.30),色温为9 424 K。