【作者】 滕晓云；

【导师】 刘彩池； 于威；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2007， 博士

【摘要】 本文采用脉冲激光沉积法(PLD)制备了晶态ZnO薄膜,研究了不同生长工艺条件和ZnO薄膜结构特性之间的关系,优化了工艺参数。在此基础上,制备了Al、Ni、Mn掺杂的ZnO基薄膜,研究了掺杂浓度对薄膜结构特性的影响。此外,采用波长为1064 nm的激光作为基频光,观测了所沉积薄膜中的二次谐波产生。采用PLD技术在c-Al2O3单晶衬底上制备出了具有高度c轴取向的ZnO薄膜,研究了衬底温度和氧气压强对薄膜结构特性的影响,给出了薄膜生长模式随生长条件变化的原因。观察到不同氧压下沉积ZnO薄膜由强的紫外发光和宽深能级发光组成的室温发光(PL)谱,揭示了薄膜的紫外发光与样品的结晶质量密切相关,而深能级发射源于电子从导带底到氧错位能级的跃迁。制备了高性能Al掺杂ZnO透明导电薄膜,研究了掺杂浓度对薄膜结构和光电特性的影响,发现适量浓度的Al掺杂有助于薄膜电阻率的降低,而薄膜的能带宽化依赖于材料中的载流子浓度。制备出过渡族金属(Ni、Mn)掺杂的ZnO基稀磁半导体(DMS)材料,观察到部分样品具有明显的室温铁磁性。给出了Zn1-xNixO薄膜磁性随掺杂浓度的变化规律,得到了Zn1-xMnxO薄膜的铁磁性与薄膜中的缺陷密切相关,合适的掺杂浓度有助于室温铁磁性的获得。以Nd:YAG激光器输出的1064 nm激光为基频光,研究了不同类型ZnO薄膜中的二次谐波产生(SHG),得到了薄膜晶粒及其边界对SHG的影响,揭示了较大掺杂浓度下Zn1-xMnxO薄膜SHG输出功率的增加来自于薄膜中存在的Mn团簇,进一步证实了过大的掺杂浓度不利于室温铁磁性的获得。更多还原

【Abstract】 The crystalline ZnO films have been deposited by the pulsed laser deposition (PLD). The relation between different deposition parameters and the structure properties of ZnO films is analyzed and the optimized condition is obtained. Based on those results, the films with Al, Ni, Mn doping in ZnO films have also been prepared and the influence of doping contents on properties of the films is studied. Furthermore, using a Nd:YAG laser as fundamental beam, the second-harmonic efficiency of the films is measured. The main results are as follows:ZnO thin films with highly c-axis orientation have been fabricated by PLD method. The influence of substrate temperature and oxygen pressure on the properties of the films is studied. The reason why the growth model of ZnO films changed with the deposition condition is explained. The room-temperature PL spectra of the ZnO films grown at different oxygen pressures have been investigated. All films show a typical luminescence behavior with a narrow ultraviolet (UV) and a broad green-yellow band. It is proposed that the intensity of UV emission depends on crystal structure and the deep level emission correlates to the electron transitions from the bottom of the conduction band to the antisite oxygen OZn.High quality Al doping ZnO transparent conductive films have been fabricated by mixing Al into ZnO target. The effect of doping concentration on their structure, electrical and optical properties is studied. The results show that the low electrical resistivity can be obtained under appropriate doping content and the optical direct band gap of films is dependent on the carrier concentration.High-quality Ni-, Mn-doped ZnO thin films have been deposited and obviously room-temperature ferromagnetic behavior is obtained. The effect of doping concentration on the ferromagnetism mechanism of Zn1-xNixO films is analyzed. The ferromagnetism of Zn1-xMnxO films is strongly related to the defects in ZnO films, but the correct doping concentration is crucial for obtaining room-temperature ferromagnetism.Using a Nd:YAG laser of 1064 nm as a fundamental beam, the second-harmonic efficiency of ZnO films have been discussed, showing that the second harmonic signal is generated not only inside crystallites, but also at grain boundaries. The increased of SHG intensity of Zn1-xMnxO films with highly doping concentration are explained by the existing of Mn cluster in the films. The declining ferromagnetism of Zn1-xMnxO films is identified.更多还原