Ju Hyun Myung

Synthesis and Characteristics of SnO2 Nanorods on Pd-Coated Substrates

We have fabricated tin oxide (SnO2) nanorods on palladium-coated substrates by carrying out the thermal evaporation of solid Sn powders. We have employed X-ray diffraction, scanning electron microscope, transmission electron microscope and photoluminescence (PL) spectroscopy to characterize the synthesized products. The obtained 1D nanomaterials with a jagged surface were SnO2 with rutile structure. PL spectra exhibited visible light emission.

Characteristics of Indium Oxide Rod-Like Structures Synthesized on Sapphire Substrates

In2O3 materials consisting of dense arrays of vertically aligned rod-like structures were deposited on sapphire substrates by thermal chemical vapor deposition (CVD) using triethylindium (TEI) and oxygen as precursors at a substrate temperature of 350 oC. The rod-like structure with a triangular cross section had a cubic structure, exhibiting preferred crystallographic orientation in the [111] direction. The photoluminescence spectra of In2O3 structures under excitation at 325 nm revealed a visible emission.

A Study of Ga2O3 Nanomaterials Synthesized by the Thermal Evaporation of GaN Powders

We have synthesized gallium oxide (Ga2O3) nanomaterials at two different growth temperatures on iridium (Ir)-coated substrates by thermal evaporation of GaN powders. The products consist mainly of nanobelts, with some additional nanosheets. The nanobelts were of a single-crystalline monoclinic Ga2O3 structure. The broad emission photoluminescence band of 900°C-products had a different peak position from that of the 970°C-products.

Appearance of Indium Oxide Nanorods in MOCVD Growth

We report on the first synthesis of nanosized In2O3 rods using the TEI as a precursor in the presence of oxygen. The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. XRD analysis revealed that the products are In2O3 phase with a tetragonal cubic structure. SEM analysis indicated that the obtained nanorods have a circular cross section and a diameter in the range of 50-150 nm.

Ga2O3 Films Grown on Sapphire by the Thermal Evaporation of GaN Powders

We have prepared the gallium oxide (Ga2O3) films on sapphire substrates by a thermal evaporation of GaN powders. We have characterized the films by using the x-ray diffraction (XRD), scanning electron microscopy (SEM), and the photoluminescence (PL). SEM and XRD revealed that the deposits were Ga2O3 thin films with monoclinic structure. PL spectrum of Ga2O3 films under excitation at 325 nm showed a blue emission.

Study of In2O3 Thin Films Prepared on TiN Substrates Using a Triethylindium and Oxygen Mixture

Indium oxide (In2O3) films was deposited on TiN substrates by the metal organic chemical vapor deposition technique using a triethylindium and oxygen mixture. The films deposited at 250-350°C were polycrystalline, while that deposited at 200°C was close to amorphous. XRD and SEM analyses indicated that the films grown at 350°C had grained structures with the (222) preferred orientation.

Structural Study of In2O3 Structures Grown by the Metalorganic Chemical Vapor Deposition

We have synthesized the film-like and rod-like structures of indium oxide (In2O3) by metalorganic chemical vapor deposition (MOCVD) method. The structural morphology of the deposits changed from the film to the arrays of 1-dimensional (1-D) materials with increasing the deposition temperature. The 1-D materials with the serrated surfaces prepared at 350°C possessed a crystalline cubic structure and had preferentially grown along the [111] direction.

Characteristics of SnO2 One-Dimensional Nanomaterials Synthesized on TiN-Coated Substrates by the Evaporation of Sn Powders

One-dimensional structures of tin oxide (SnO2) on TiN-coated substrates were obtained by simple heating of Sn powders. X-ray diffraction, high-resolution transmission electron microscopy, and the selected area electron diffraction showed that 1D structures are composed of SnO2 with rutile structure. The photoluminescence of the structures in the visible region suggests possible applications in nanoscaled optoelectronic devices.

Structural Properties of Sputter-Deposited ZnO Thin Films Depending on the Substrate Materials

We have demonstrated the growth of ZnO thin films with c-axis orientation at room temperature on various substrates such as Si(100), SiO2, and sapphire by the r.f. magnetron sputtering method. X-ray diffraction (XRD) and scanning electron microscopy altogether indicated that the larger grain size and the higher crystallinity were attained when the ZnO films were deposited on sapphire substrates, compared to the films on Si or SiO2 substrates. The c-axis lattice constant decreased by thermal annealing for the ZnO films deposited on Si or SiO2 substrates, while increased by the thermal annealing for the ZnO films grown on sapphire substrates.