【作者】 王伟娜；

【导师】 方庆清；

【作者基本信息】 安徽大学 ， 材料学， 2010， 硕士

【摘要】 ZnO是Ⅱ-Ⅵ族宽禁带氧化物半导体材料,属于六角纤锌矿结构,具有较大的激子束缚能,可以实现室温下的紫外受激辐射。它的化学性质稳定,带隙达到3.37eV,非常适用于短波长光学器件,是目前极具发展潜力的电子材料之一。最近研究发现,在ZnO中掺杂Mg、Cd可以改变ZnO的带隙,将有利于器件的光学参数调制。因此,制备出适合紫外光电器件需要的光学性能可以调制的高质量ZnO薄膜有着非常重要的科学意义和应用价值。本文利用脉冲激光沉积(PLD)方法在单晶Si(100)衬底上制备出高c轴取向,其蓝绿发光峰几乎被完全抑制,适合紫外光器件的高质量MgkZn1-xO薄膜。文章着重围绕ZnMgO薄膜的PLD制备工艺过程系统开展结构、光学、磁学性能改性研究,主要研究内容如下：1、系统研究了利用脉冲激光沉积方法在Si(100)衬底上制备高质量Zn1-xMgxO单晶薄膜的工艺过程,获得了高致密度生长的单晶Zn1-xMgxO薄膜。在背景真空度5×10-4 Pa、沉积时间为40min条件下,薄膜的紫外发射峰强度非常高,缺陷发光峰几乎被完全抑制,具有良好的可重复性,适合于光学器件的应用。2、在有氧条件下,系统研究了氧压对Zn1-xMgxO薄膜样品结构、光学和磁学特性的影响。实验发现,适量的氧气可以减少晶体缺陷,减小膜的内应力,提高薄膜的结晶质量。并且发现,氧压导致紫外发光峰移动,在0.7Pa氧压下,样品相对于8Pa样品的紫外发光峰蓝移了5.3nm。我们还研究了氧压对磁性的影响,发现薄膜样品的饱和磁化强度呈现出先增大后减小的变化。3、研究了Co, Mg共掺杂对ZnO薄膜磁性的影响,实验发现,随着Co含量的增加,薄膜的饱和磁化强度随之增加。我们认为Co2+离子的3d电子的交换耦合导致了薄膜磁性的增强,这与载流子激发铁磁性的交换理论模型是一致的。4、同时,我们还系统的研究了氮分压对Zn1-xMgxO薄膜样品结构、光学和磁学特性的影响。X光衍射谱分析发现,摇摆曲线的半高宽随着N分压的增加变宽,表明N的掺入导致薄膜外延生长变差,缺陷增多。实验发现,随着氮含量的增加样品的紫外发光峰强度减弱,绿光带增强。在5Pa的N压下,ZnMg0.075O样品的紫外发光峰和可见发光带连成一片,形成一个发光带。而在20Pa和35Pa的N压下,样品未见到紫外峰位的发生移动,但蓝绿缺陷峰强度明显增强。我们认为,N掺杂对生长高质量的ZnO薄膜和紫外发光性能是不利的。更多还原

【Abstract】 ZnO is a wide direct band gap semiconductor and has a wurtzite structure. It has comparatively large exciton binding energy (60meV) and is capability of emiting ultraviolet at the room temperature. The high quality ZnO thin film is one of most potential membranous materials at present. Zinc oxide with a high stability and a direct band gap of 3.37eV has greatly attracted attention because of its high potential for application as short wavelength optical devices. In recent studies, it is found that doping Mg or Cd can change the width of band gap of ZnO films. This will be very beneficial to the modulation of optical parameter of optoelectric devices. Therefore, the ZnMgO thin films, which are fit for optoelectric devices and optical properties, can be modulated by adding a differact content of Mg, have a very important scientific significance and value of applicationIn this paper, the highly c-axis oriented Zn1-xMgxO thin films which is fit for optical devices were grown on the Si(100) substrates by pulsed laser deposition (PLD) technique, and its defect emission was almost inhibited completely. The article focused on the PLD preparation process and improving of microstructural, optical and magnetic properties of ZnMgO thin films. The main contents can be summarized as follows:1. Highly c-axis oriented Zn1-xMgxO thin films were deposited on Si (100) substrates in oxygen atmosphere. It is found that in 5×10-4 Pa of a base pressure, the film with a deposited time for 40 min is a high-density and has a strong UV emission peak, and its defect emission is almost inhibited completely.2. We study of the effect of oxygen pressure on the structure of Zn1-xMgxO thin films, optical and magnetic characteristics. Appropriate amount of oxygen is beneficial to improving surface structure of film, reducing the crystal defects and the internal stress of films. With the increase of oxygen pressure diffraction peak half-width also will be increased, the diffraction peak intensity have also shown a tendency to lower and increases after, the saturation magnetization of samples showing a trend of increased first and then decreased. The UV emission peak of 0.7Pa sample relative to the sample 8Pa has a blue-shift of 5.3nm. We also studied the influence of oxygen pressure on the magnetic properties and found that the saturation magnetization of thin films showing the changes first and then decreased.3. In addition, we also examined the effect of Co-doping content on magnetic properties of ZnMgO thin films. It is found that with the increase of Co content, the saturation magnetization of thin films also increased. Through the XRD image, we can see that there is no Co impurities peak. So Co2＋ions are successfully doped into the lattice of Zn1-xMgxO films. This is consistent with the carrier magnetic excitation exchange of theoretical models.4. The effect of nitrogen partial pressure on the Zn1-xMgxO films structure, optical and magnetic characteristics are studied. FWHM of diffraction peaks increases with the increase of N partial pressure. The incorporation of N led to the deterioration of films’epitaxial growth and the number of defects increased. The UV peak and visible light luminescence is band together to form a luminous band of N: ZnMg0.0750-5Pa samples. The UV peak has no moving with N:ZnMg0.075O (20Pa, 35Pa) samples than the non-nitrogen-doped samples, while the blue-green defect peak intensity obviously increased. With the increase of nitrogen content the intensity of UV peak reduced and the green light enhanced. This is mainly due to an increase in N content led to an increase in defects and deteriorated crystalline quality.更多还原