Realizing Shallow Acceptor Levels in Delafossite CuAlO₂ (112−0) Surfaces by Chalcogen Doping

First-principles calculations of chalcogen doping at the delafossite CuAlO₂ ((Formula presented.)) surfaces have been performed. The calculated results indicate that the bigger the atomic radius of doping atom (compared with that of O atom) is, the more difficult is the doping process; and the doping process becomes more and more difficult from the surface to the interior of CuAlO₂ ((Formula presented.)) surfaces. The energetic favorability of doping is the best under Al-rich condition. The work function of chalcogen doping has been calculated, showing that the S-2 surface has the lowest work function. The band structures and density of states of pure and chalcogen doped CuAlO₂ ((Formula presented.)) surfaces have been given, where the bandgaps, shifts of energy levels, and potential shallow acceptor levels have been analyzed and discussed.