EFFECTS OF POSTGROWTH TREATMENT AND COATING WITH ULTRATHIN METAL LAYERS ON THE BAND BENDING AND FIELD ELECTRON-EMISSION OF DIAMOND FILMS

Band bending formation on thin nanocrystalline diamond films and field electron emission after post-growth treatments was investigated. It w as found that treatment of the diamond surface with hydrogen plasma su bstantially decreases the density of point defects, forms the downward band bending and enhances the field electron emission from the films. in the case of an argon plasma treated diamond surface, new point def ects were induced and their energy distribution was changed. Neverthel ess, the downward band bending was formed and the field electron emiss ion was enhanced similar to the H-plasma-treated diamond surface with minor density of defects. These effects were interpreted in terms of t he electrical dipole formation on the plasma treated diamond surfaces. Coating the diamond films with ultrathin metal (Ni, Ti) layers reveal ed the dependence of the band beading and field emission behavior on t he type and thickness of the metal used. The deposition of a few monol ayers of Ni on the diamond surface was found to raise the position of the Fermi level relative to the valence band maximum and cause the dow nward band bending, reducing the field emission threshold. It was sugg ested that the charge of the surface dipoles an the metal coated diamo nd surfaces (as in the case of the H and Ar plasma treatments) plays a key role in the band bending formation. (C) 1998 American Institute o f Physics. [S0021-8979(98)02315-9].