Papers by Author: Shu Lin Gu

Abstract: GaN films are grown on Si(111) with low-temperature GaN (LT-GaN) layers as buffer layers by hydride vapor phase epitaxy (HVPE). The LT-GaN layers are deposited at different temperatures ranging from 400 to 900 °C. The surface property, the structure and optical properties of the GaN films with different LT-GaN layers are studied. When deposition temperature of LT-GaN layer is 600 °C, the GaN film shows the best properties.

Abstract: Fe films have been grown on different oriented Si substrates by metal organic chemical vapor deposition (MOCVD), and then samples are put in the air without any protection for nearly fifteen years. In this paper, using methods such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM), we make a detailed research on the samples. We identify the composition and structure of the epitaxial films on different oriented substrates and compare the difference both in composition and magnetic properties. Different orientation of the substrates results in different epitaxial film with different characteristic. We also confirm the existence of single crystal iron in the heteroepitaxial film grown on Si (001), and discuss the possible reason why the single crystal iron film still exists without complete oxidation in air for such a long time.

Abstract: The MOCVD-growth and annealing of InN films have been studied in this work. The XRD spectra of InN films grown at 350 °C~500 °C indicate that the diffraction of In increases with increasing the growth temperature to 425 °C and the temperature higher than 425 °C causes the decrease of In diffraction. The corresponding SEM images show that In grains disappear from the surface as the growth temperature is higher than 425 °C. These are attributed to the increase of the desorption of In with the growth temperature. In addition, the SEM images of the annealed InN films also show that the In grains decrease gradually as the annealing temperature is higher than 425 °C. Thus, it is concluded that the desorption of In is the main process as the temperature is higher than 425 °C.

Abstract: In this paper we have characterized the performance of a vertical metalorganic chemical vapor deposition (MOCVD) reactor used for deposition of ZnO thin films. The equations of the mathematical model are solved numerically using a control-volume-based finite difference method. A two-dimensional model is put forward to study the dependence of the growth rate on the inlet flow rate and susceptor temperature. The mass-fraction distribution of the reactants has been studied as a function of the position above the substrate, which shows that gas phase pre-reaction in our reactor is well confined. The simulation results are useful for the practical growth of ZnO.

Abstract: The morphology evolution of ZnO films grown on sapphire (0001) by MOCVD have been studied as a function of buffer growth time and temperature by means of atomic-force microscope (AFM), x-ray diffractions (XRD) and optical microscopy. When the buffer growth temperature decreased to 450°C, the surface became smooth greatly, indicating the transition from typical 3D island growth to quasi-2D growth mode. As the buffer growth time exceeds 5min, the micron-sized pit-like features are formed. It is due to the lack of stabilization of adatoms under the “etching” action of ionized O2/Ar during high temperature buffer annealing