Preparation of MgO Films as Buffer Layers by Laser-ablation at Various Substrate Temperatures

MgO thin films were deposited on Si（100） substrates by laser ablation under various substrate temperatures （Tsub）,expecting to provide a candidate buffer layer for the textured growth of functional perovskite oxide films on Si substrates.The effect of Tsub on the preferred orientation,crystallinity and surface morphology of the films was investigated.MgO films in single-phase were obtained at 473-973 K.With increasing Tsub,the preferred orientation of the films changed from （200） to （111）.The crystallinity and surface morphology was different too,depending on Tsub.At Tsub=673 K,the MgO film became uniform and smooth,exhibiting high crystallinity and a dense texture.

The Effects of Annealing and Discharging on the Characteristics of MgO Thin Films Prepared by Ion Beam-Assisted Deposition as a Protective Layer of AC-PDP

This study investigated the effects of annealing and discharging on the characteristics of MgO thin films prepared by ion beam-assisted deposition as a protective layer of AC-PDP. By an annealing process at a temperature of 450 ℃ for more than three hours, the crystallinity of the deposited MgO films was improved, but the surface of the （200）-oriented MgO thin films in the vicinity of the discharge electrodes, especially on the inner sides of the electrodes, was subjected to crack formation to the compressive stress of The failure mechanism of the MgO films plus the additional （200）-oriented MgO films was due compressive stress induced by the differences in the coefficient of thermal expansion between the electrode and the dielectric layer. In the discharging process, all MgO films were eroded unevenly, and the serious erosion occurred near the edges of the discharge electrodes. ATM（atomic force microscopy） images show that the eroded surface of the （200）-oriented MgO thin film is smoother than that of the （111）-oriented fihn. Also, the （200）-oriented MgO thin film shows an improved ability to resist ion erosion compared to the （111）-oriented film.

Growth of MgO Thin Film on Silicon Substrate by MOCVD

Highly oriented MgO(111)and MgO(100)thin films have been deposited on Si(111)and Si(100)substrates by using Low Pressure MOCVD(LPMOCVD).Magnesium 2,4-pentanedionate was used as the source ma- terial.The films have a very smooth surface morphology and optical transparency with an index of refraction of 1.71(632.8 nm).Typical growth rate of the films is 1.0 μm/h.The data of X-ray diffraction analysis indi- cate that the films are fully textured with(111)and(100)orientation perpendicular to the substrate surface respectively.The main parameters having influence on the deposition are the substrate temperature,the total pressure in the reaction chamber,the reaction gases and its flowrate.

Plasma-Neutral Gas Structure in a Magnesium Cathodic Arc Operating at Oxygen Gas with Experimental Comparison

The plasma-neutral gas structure generated in a magnesium cathodic arc operated with oxygen gas at a constant current of 50 A has been investigated by employing a simplified one-dimensional fluid model. The model includes elastic collisions and charge-exchange reactions between metallic particles and gas molecules, and also generation and recombination of gaseous ions by electron impact. The distribution profiles of density and velocity of species along the axial direction were obtained at different background gas pressures （in the range of 0.7-3.0 Pa） by this model. A comparison with the experiments was made. At lower gas pressures, the depositing particles were mainly the metallic ions with a larger kinetic energy. As the gas pressure increased, the magnesium atoms with smaller kinetic energy acted as the dominant depositing species. Determined by the minimization of the system＇s total energy, MgO（100） or/and MgO（110） orientation appeared easily in the MgO films at lower gas pressures, and at higher gas pressures, the film preferred orientation was MgO（111）.