Optical absorptions, electrical properties and related band structures of diamond with high-dose B, C, N or P implantation at elevated temperatures

抄録

In this paper, we report investigations on optical and electrical properties of diamond implanted with high dose (up to ～10²¹ cm^-3) B, C, N or P at elevated temperatures in the energy range 30-175 keV and post-implantation annealed, and discuss their related band structures. It is known that the high-dose ion implantation over critical dose D_c to diamond about room temperature results in graphitization after a post-implantation annealing process. In contrast to that, it is revealed that any diamonds B-, C-, N- and P-implanted at high doses at elevated temperatures (～400 ℃) maintain diamond structures (graphitization does not occur) after annealing. In the cases of B and N, not only graphitization is avoided but also their resistivities are reduced after annealing. In the B doped sample, electrical activation of B impurity to its valence band occurs and becomes a p-type degenerate semiconductor. In the N doped sample, the resistivity is ～10³ times as high as that in the B doped sample, but the value is much lower than a C implanted sample formed in this study. This suggests that in the N doped sample impurity band conduction related to nitrogen (including nitrogen-vacancy complexes) occurs unlike the B doped sample. The resistivity of the P doped sample is ～10⁶ times as high as that of the N doped sample.