Atomic investigation of individual apexes of diamond emitters by a scanning atom probe

Diamonds grown by chemical vapor deposition and high-pressure high-temperature processes were mass analyzed by a newly developed scanning atom probe. The mass analysis of the diamonds revealed that the diamonds contain a large amount of hydrogen not only in the surface layer but also in the deep underlying layers and that carbon atoms form the clusters, C3, C5, C8, and C16. The clustering carbon atoms could be strongly bound in the diamond structure. The detection of a large number of neutral particles indicates that most cluster ions were decomposed into a positive ion and a neutral particle immediately after field evaporation. The interesting finding is that most carbon atoms are field ionized as multi-ionized ions such as C2+, C3+, and C4+ and/or CH2+, CH3+, and CH4+ with the mass peak of H+, while the major mass peaks are C+ and/or CH+ when no hydrogen peak is found. This may suggest that the binding state of carbon atoms in the diamonds varies with the binding state with hydrogen atoms.