Scanning tunneling microscopy of the electronic structure of chemical vapor deposited diamond films

Scanning tunneling microscopy has been used to characterize the electronic structure and surface morphology of diamond films grown using the hot filament and microwave plasma chemical vapor deposition techniques. We observe a significant difference between the current-voltage (I-V) curves for the two types of films. The I-V curves for the hot-filament grown films are characterized by a well-defined zero-current region from which a surface band gap of 4.1 eV is measured. The I-V curves for the microwave plasma grown films exhibit a rectifying behavior which can be modeled by surface band bending. We compare the surface density of states obtained from the I-V curves with those obtained from x-ray photoelectron and appearance potential spectroscopies.