Repair of defects created by Ar + sputtering on graphite surface by annealing as confirmed using ToF-SIMS and XPS

Defects were created on the surface of highly oriented pyrolytic graphite (HOPG) by sputtering with an Ar+ ion beam, then characterized using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) at 500 degrees C. In the XPS C1s spectrum of the sputtered HOPG, a sp(3) carbon peak appeared at 285.3eV, representing surface defects. In addition, 2 sets of peaks, the C-x(-) and CxH- ion series (where x=1, 2, 3...), were identified in the ToF-SIMS negative ion spectrum. In the positive ion spectrum, a series of CxH2+center dot ions indicating defects was observed. Annealing of the sputtered samples under Ar was conducted at different temperatures. The XPS and ToF-SIMS spectra of the sputtered HOPG after 800 degrees C annealing were observed to be similar to the spectra of the fresh HOPG. The sp(3) carbon peak had disappeared from the C1s spectrum, and the normalized intensities of the CxH- and CxH2+center dot ions had decreased. These results indicate that defects created by sputtering on the surface of HOPG can be repaired by high-temperature annealing.