Optical and electrical properties of aluminum-doped ZnO thin films grown by pulsed laser deposition

Transparent aluminum-doped zinc oxide (AZO) thin films were deposited on quartz glass substrates by pulsed laser deposition (PLD) from ablating Zn-Al metallic targets. The structural, electrical and optical properties of these films were characterized as a function of Al concentration (0-8 wt.%) in the target. Films were deposited at a low substrate temperature of 150 °C under 11 Pa of oxygen pressure. It was observed that 2 wt.% of Al in the target (or 1.37 wt.% of Al doped in the AZO film) is the optimum concentration to achieve the minimum film resistivity and strong ultraviolet emission. The presence of Al in the ZnO film changes the carrier concentration and the intrinsic defects.     

热蒸发法制备ZnO纳米棒阵列

氩气氛常压下，利用热蒸发法，在无催化剂、无ZnO预沉积层的硅衬底上制备了取向良好，排列整齐的ZnO纳米棒阵列．在距Zn源不同位置的Si衬底上得到了不同形貌的样品．硅衬底置于锌源正上方是得到取向一致的ZnO纳米阵列的一个关键性条件．用场发射扫描电子显微镜、X射线粉末衍射表征样品表面形貌、晶体结构．进一步研究了样品的生长机制和荧光性质．     

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     

反应磁控溅射ZnO/MgO多量子阱的光致荧光光谱分析

采用反应射频磁控溅射方法，在Si(001)基片上制备了具有高c轴择优取向的ZnO/MgO多量子阱.利用X射线反射、X射线衍射、电子探针，光致荧光光谱等表征技术，研究了ZnO/MgO多量子阱的结构、成份和光致荧光特性.研究结果表明，多量子阱的调制周期在1.85—22.3 nm之间，所制备的多量子阱具有量子限域效应，导致了室温光致荧光峰的蓝移，并观测到了量子隧穿效应引起的荧光效率下降.建立了基于多声子辅助激子复合跃迁理论的室温光致荧光光谱优化拟合方法，通过室温光致荧光光谱拟合发现，ZnO/MgO比ZnO/ZnMgO多量子阱具有更大的峰位蓝移，探讨了导致光致荧光光谱展宽的可能因素. 关键词： ZnO/MgO 多量子阱 磁控溅射 光致荧光 量子限域效应     

Al掺杂原子分数及退火温度对ZnO薄膜光学特性的影响

 采用溶胶凝胶法在（0001）Al₂O₃衬底上制备了不同掺杂原子分数的ZnO:Al薄膜，在Ar气氛中进行了600～950 ℃不同温度的退火处理，研究了掺杂原子分数和退火温度对薄膜光致发光、光吸收和透射的影响。结果显示，薄膜的紫外峰强度随掺杂原子分数和退火温度的提高而增强，与缺陷相关的绿光强度却随着掺杂原子分数和退火温度的提高而降低；薄膜光学带隙随掺杂原子分数的提高从3.21 eV增大到3.25 eV；光吸收在可见光区随着退火温度的升高而增大，在紫外区却随着退火温度的升高而减小，透射与吸收的变化规律相反；薄膜吸收边随退火温度的升高出现轻微的红移。     

Structural and photoluminescent properties of ZnO films deposited by radio frequency reactive sputtering

Zinc oxide films with c-axis preferred orientation were deposited on silicon (100) substrates by radio frequency (RF) reactive sputtering. The properties of the sam- ples were characterized by X-ray diffractometer, X-ray photoelectron spectroscopy and fluorescent-spectrophotometer. The effect of sputtering power and substrate temperature on the structural and photoluminescent (PL) properties of the ZnO films was investigated. The results indicated that when the sputtering power is 100 W and the substrate temperature is 300-400℃, it is suitable for the growth of high c-axis orientation and small strain ZnO films. A violet peak at about 380 nm and a blue band at about 430 nm were observed in the room temperature photolumines- cence spectra, and the origin of blue emission was investigated.     

p型ZnO薄膜的制备及特性

采用射频磁控溅射在Si片上制备ZnO薄膜，通过离子注入对样品进行N掺杂，在不同温度下进行退火并实现了p型转变.用扫描电子显微镜、X射线衍射和Hall测量对薄膜进行了表征，结果表明薄膜具有良好的表面形貌和高度c轴择优取向，退火后p型ZnO薄膜的最高载流子浓度和最低电阻率分别为1.68×10¹⁶cm^-3和41.5Ω·cm.讨论并分析了退火温度和时间对ZnO薄膜p型转变的影响.     

电化学沉积高c轴取向ZnO薄膜及其光学性能分析

采用阴极还原方法，在透明导电玻璃(ITO)上制备了高c轴择优取向的ZnO薄膜.通过X射线衍射、扫描电子显微镜等表征技术，研究了沉积电流对ZnO薄膜的结构、应力状态及表面形貌的影响；利用光致荧光光谱及透射光谱等分析方法，探讨了沉积电流变化对ZnO薄膜的光学性能的影响.研究结果显示：各沉积电流下均可制得高c轴取向的ZnO薄膜；薄膜表面形貌受电流的影响较大；从透射谱可以看出，薄膜在可见光波段有较高透射率，且薄膜厚度随沉积电流的增大而增大.光致荧光测量表明，电化学沉积的ZnO薄膜具有明显的带隙展宽.而且，随着沉积电流的增加，带隙发光强度逐渐减弱，缺陷发光逐渐增强.     

Photochemical synthesis of ZnO/Ag nanocomposites

Composite ZnO/Ag nanoparticles have been formed via the photocatalytic reduction of silver nitrate over the ZnO nanocrystals, their optical, electrophysical and photochemical properties have been investigated. Mie theory has been applied to analyze the structure of the absorption spectra of ZnO/Ag nanocomposite. The irradiation effects upon the optical properties of ZnO/Ag nanostructure have been investigated. It has been found that the irradiation of ZnO/Ag nanoparticles results in electrons accumulation by both the semiconductor and the metallic components of the nanocomposite. It has been found that silver nitrate can be photochemically deposited onto the surface of ZnO nanoparticles under the illumination with the visible light in the presence of the sensitizer – methylene blue. Kinetics of the sensitized Ag(I) photoredution has been studied. It has been concluded that the key stage of this process is the electron injection from singlet-excited methylene blue molecule into ZnO nanoparticle.     

Photoinduced growth of Cu nanoparticles on ZnO from CuCl<Subscript>2</Subscript> in methanol

Cu nanoparticles were formed on surface of nano-ZnO by UV light induced photoreduction of CuCl₂ in methanol solution suspended with ZnO nanoparticles. By controlling the reaction conditions, the average size of the produced copper nanocrystal can be fine-tuned in the range of 10–200 nm. At constant UV irradiation, the Cu nanocrystals gradually grew up as the initial concentration of copper cation was increased, showing that the in situ formed Cu nanoparticles act as a bridge to facilitate the transferring of photoexcited electrons from ZnO surface to Cu²⁺ in solution. A Redox property was also proved for the Cu nanoparticles.