Local Atomic Structures around Implanted Phosphorus Atoms in Diamond Analyzed by X-ray Absorption Near Edge Structure

Formation of highly controlled p-type and n-type conductive layers in diamond by ion implantation technique has been strongly desired for realizing diamond-based electronic devices for decades; however practically available doping condition has not been found especially in n-type doping. In this study, we comprehensively determined the local structures and depth profiles of implanted P atoms as n-type dopant to find out the origin of inactivation of implanted P atoms. The local structure around the implanted P atoms was analyzed by X-ray absorption fine structure using synchrotron-radiation-light and the first-principle calculation based on density functional theory. We found at least four components for all prepared samples in the near edge X-ray absorption structure, suggesting that implanted P atoms locate in four different chemical environments. We eventually assigned all the components by comparing the simulated X-ray absorption with the first-principle theoretical calculation: one of the components corresponds to active phosphorus atom in the substitutional site, and others are the elemental P-P bonds and some defect complexes probably acting as inactive species for n-type dopant. These facts suggest that the knowledge of local structure of implanted P atoms and control of them are substantially important to reduce the inactivation factors of the implanted dopants.