Possibility of carbon nitride formation by low-energy nitrogen implantation into graphite: <i>In</i> <i>situ</i> electron spectroscopy studies

Abstract

The possibility of carbon nitride formation by low-energy nitrogen ion irradiation of graphite was investigated by in situ x-ray photoelectron spectroscopy. Room-temperature and hot 500-eV N+2 implantations were performed with saturation doses for which a constant nitrogen concentration was obtained. Analysis of the N(1s) core level line indicates the existence of three different carbon–nitrogen bonding states in the room-temperature implanted layer. Annealing experiments up to 500 °C revealed a slight, gradual decrease of nitrogen concentration in the implanted layer accompanied by a partial redistribution of the nitrogen bonding states. Hot nitrogen implantations at 300 and 500 °C resulted in a predominant population of the more covalent, with higher N(1s) binding energy, nitrogen bonding state. Such a distribution of carbon–nitrogen chemical bonds could not have been obtained by annealing of the room-temperature implanted layer. These results may be of importance in finding a way to produce the elusive β-C3N4 phase by ion beam assisted deposition.