Two different species of deuterium implanted into a pyrolytic graphite observed by XPS–SIMS

Abstract

Trapped states of deuterium implanted into a pyrolytic graphite with 5 keV were investigated by means of the x-ray photoelectron spectroscopy and the secondary ion mass spectrometry. Chemical shift and broadening of C 1s peak were observed in the XPS spectra due to deuterium-ion implantation at room temperature. The shift and the broadening increased with the deuterium fluence to reach constant values. In the SIMS spectra, CD− and C2D− peaks appeared due to the deuterium implantation. The intensity of the CD− peak increased with the fluence to reach a constant value, whereas that of the C2D− peak passed through a maximum to decrease to a constant value. A linear relation was observed between the chemical shift and the CD− peak. The chemical shift and the CD− peak disappeared after annealing the sample at 600 °C for 5 min, whereas the broadening of the C 1s peak and the C2D− peak disappeared after annealing the sample at 900 °C for 5 min. On the basis of these observations, it is concluded that at least two different species of the deuterium are formed in the graphite due to the deuterium implantation.