Atomic-scale study of graphene and electroluminescence properties of PTCDI on 6H-SiC(0001) Surface by scanning tunneling microscopy

6H-SiC (0001), a wide band gap material, is used to make graphene and study the luninescence property of PTCDI molecules. Among several methods to grow grapheme, epitaxial growth method on Sic is a UHV (Ultra High Vacuum) process and has many advantages in STM study of graphene. We could observe atomic arrangement of graphene edges ant its influence on electron scattering near those edges. This was possible because we made the clean grapheme in UHV STM chamber. Another interesting measurement was conducted to see the vertical structure of this epitaxial grapheme. Z-V spectroscopy enabled us to investigate the electronic interfaces of the epitaxial grapheme very precisely. Luminescence of a single molecule, PTCDI, was studied on SiC surface. Thin insulating layer has played an important role in this field, but we tried a new way by using wide band gap material. We expected that the molecular orbitals involved in the luminescence are located within the band gap and this would decouple the molecules from the substrate. Two spectroscopy methods, I-V, I-Z were used to quantitatively study the resulting electronic structure and their roles for the light emission. Trapped carrier dynamics was studied on dielectric nanodots grown by plasma enhanced chemical vapour deposition (PECVD) and on silicon oxide grown by pulsed laser deposition (PLD) on Si wafer. Carrier dynamics can be explained with a model based on Coulomb interaction with the boundary conditions of the nanodot structure. The trapped charge can be estimated quantitatively from the measured trap dynamics, elucidating the electrostatic effect in a small dielectric system.