ELECTRON-BEAM MODIFICATION OF THE SCHOTTKY DIODE CHARACTERISTICS OF DIAMOND

Electron beam irradiation from a scanning electron microscope has been shown to improve the rectification characteristics of a boron doped diamond sample, as evidenced by measurement of a lowered reverse current in Al Schottky diodes. The sample processing procedure consisted of cleaning in heated CrO3/H2SO4 and NH4OH/H2O2 Mixtures, exposure to an electron beam, a post-exposure cleaning in NH4OH/H2O2, and metallization. Since published information on the effect of CrO3/H2SO4 and NH4OH/H2O2 mixtures on the diamond surface is lacking, we hypothesize that the exposure of the diamond surface to an electron beam releases hydrogen from the surface, while the post-irradiation clean in boiling NH4OH/H2O2 may oxygenate the diamond surface. This result is consistent with previous work which demonstrated that annealing in hydrogen and oxygen ambients affected the surface resistance of diamond. These results indicate a high surface resistance is necessary to form good Schottky junctions in diamond.