Density functional theory study of Al, Ga and In impurities in diamond

As a consequence of its high atomic number density, diamond can incorporate a relatively limited range of impurities as distributed point-defects, chiefly N, B and H. A few other species can be grown-in, and other impurity species incorporated via implantation and annealing. For applications including electronic, electrical and quantum devices, the presence of states deep within the wide band-gap is of importance, and the list of potential colour centres available for exploitation continues to grow. Although B can be grown into diamond at high concentration, study of other group-13 elements is rather limited. In this paper we present the results of modelling of Al, Ga and In. We find all species readily form complexes with vacancies, and exhibit electronic structures that parallel those of the Si-V complex. We report electronic structures, electrical levels, optical transitions and hyperfine interactions of the colour centres, as well as reflect upon the thermodynamics of the complexes. We suggest that co-implanting group-13 elements with nitrogen would give rise to the defect charge states with potential for quantum applications.