Studies On The Preparation Technics Of PLD And Properties Of Mg, Co Doped ZnO Thin Films

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.