Ab Initio Study of Donor–Hydrogen Complexes for Low-Resistivity n-Type Diamond Semiconductor

We performed local density approximation (LDA)-based ab initio calculations for isolated substitutional donor impurities (phosphorus single donor and sulfur double donor), hydrogen at various sites, and hydrogen-related complexes (phosphorus-hydrogen and sulfur-hydrogen) in diamond. Their stable atomic configurations and electronic structures were determined. The two donor impurities exhibit Jahn–Teller distortions, reducing their symmetries from T d to C 3 v . We found that the bond center site is the most stable site for hydrogen (and muonium) in diamond, and the tetrahedral interstitial site, the hexagonal interstitial site, and the antibonding site are metastable sites. This result is consistent with those of muon-spin-rotation (µSR) experiments. We also found that hydrogen passivates phosphorus donor. We propose a bonding model for the sulfur–hydrogen complex which produces a shallower single-donor level (1.07 eV below the bottom of the conduction band) than the isolated sulfur double-donor (1.63 eV). Frequencies of infrared active hydrogen vibration which will be observed by infrared absorption measurements and the cohesive energy of each complex was predicted. Finally, we propose a new doping method for the fabrication of low-resistivity n -type diamond.