Space charge limited current (SCLC) as observed on diamond surface damaged by MeV ion implantation

Space charge limited currents (SCLC) were observed on diamond surfaces that were damaged by mega-electron volt (MeV) ion implantations. The current-voltage plots display an exponential behavior with a fitting constant alpha, whose value was found to increase with thermal annealing temperatures up to 600 degrees C. Comparisons among the surface areas implanted with different ion fluences indicate that there exists a damage threshold, above which the SCLC occur, and below which Ohmic conduction dominates. Raman spectroscopy studies confirm that the measured conductance originates from the vacancies created in the shallow surface layers, in agreement with Baskin's model [1]; furthermore, the spectra show that the trapped space charges could be related to the interstitials in the surface layers, which may form a localized field in opposition to the drift current flow.