Scanning tunneling microscopy and spectroscopy of non-doped, hydrogen terminated CVD diamond

The electron emission from a diamond surface is influenced by the surface t ermination and the surface density of states. It is known that the hydrogen termination of diamond surfaces induces p-type conduction. Scanning tunnel ing spectroscopy (STS), combined with high-resolution topographical imaging with the scanning tunneling microscope (STM), enables to investigate local variations in the electronic structure of surfaces. We show that the hydro gen termination is sufficient to obtain reproducible STM and STS measuremen ts. We find that the formation of a Schottky point contact between tip and sample gives rise to a rectifying I-V characteristic. Retracting the tip re sults in a change in the I-V characteristics from a rectifying behavior tow ards normal tunneling behavior. The tunneling measurements confirm the surf ace p-type conductivity and Fermi level pinning at the valence band.