Investigation on Potential Barrier of Terminal Pinned Schottky Junction

The diamond Schottky theory needs to be further improved before exertising its full advantages, especially in terms of the physical properties of the diamond surface and the interface between metals and diamond. In our previous work, we experimentally verified that the oxygen terminal with a ketone bond introduces an acceptor surface state, 2.22 eV above valence band maximum (VBM), into bandgap at a diamond surface. Here, we further investigated the contact band diagram between metals (Au, Ag, Pt, W, and Pd) with different work function and oxygen terminated diamond using X-ray photoelectron spectroscopy. Results showed that the contact Fermi level was at 2.38 eV, 2.33 eV, 2.32 eV, 2.28 eV, and 2.29 eV above VBM, respectively. In addition, the similar symmetrical photocurrent-voltage characteristics under positive and negative bias were observed between Au-Ag and Ag-Pt electrodes deposited on the same oxygen terminated diamond plate. All the data above could be drawn a conclusion that the oxygen-terminal can pin the Schottky barrier height. We believe that the results obtained herein will help in the design and theoretical analysis of diamond Schottky devices