Papers by Author: Jeong Yong Lee

Abstract: ZnO semiconductor has a wide band gap of 3.37 eV and a large exciton binding energy of 60 meV, and displays excellent sensing and optical properties. In particular, ZnO based 1D nanowires and nanorods have received intensive attention because of their potential applications in various fields. We grew ZnO buffer layers prior to the growth of ZnO nanorods for the fabrication of the vertically well-aligned ZnO nanorods without any catalysts. The ZnO nanorods were grown on Si (111) substrates by vertical MOCVD. The ZnO buffer layers were grown with various thicknesses at 400 °C and their effect on the formation of ZnO nanorods at 300 °C was evaluated by FESEM, XRD, and PL. The synthesized ZnO nanorods on the ZnO film show a high quality, a large-scale uniformity, and a vertical alignment along the [0001]ZnO compared to those on the Si substrates showing the randomly inclined ZnO nanorods. For sample using ZnO buffer layer, 1D ZnO nanorods with diameters of 150-200 nm were successively fabricated at very low growth temperature, while for sample without ZnO buffer the ZnO films with rough surface were grown.

Abstract: The X-ray diffraction (XRD) pattern for the ZnO films grown on Si (100) substrates indicates that the grown ZnO films have a strong c-axis orientation. The pole figure indicates that ZnO thin films have columnars with the grains of the [0002] crystallographic axis perpendicular to the Si (100) substrate, indicative of the random rotational orientations along the c-axis. Selected area electron diffraction pattern (SADP) of the ZnO/Si (100) heterostructures shows that the ZnO preferential oriented film is formed on the Si substrate. A possible atomic arrangement of the crystal structure and the formation mechanism of the c-axis orientated ZnO thin films grown on p-Si substrates are discussed on the basis of the XRD, the pole figure, and SADP results.