Lithium implanted into diamond: Regular trends and anomalies

Diamond single crystals implanted with 7Li+ ions within broad range of fluences including those higher graphitization threshold were studied by secondary ion mass spectrometry (SIMS) and optical interference profilometry. It has been shown that sputtering coefficient of diamond does not depend on the level of radiation damage and on the microstructure of the material, which may be due to the formation of an amorphous layer on the surface during the ion bombardment. Graphitization domains were observed immediately after high-fluence ion implantation, prior to annealing. No diffusion of implanted lithium (at any fluences) was observed in diamond both at high-temperature treatment and under strong photothermal excitation near the ablation threshold. SIMS measurements have shown sharp decrease of lithium ion yield in strongly damaged diamond, particularly in graphitized region, which has not yet been satisfactorily explained.