COLUMN-V ACCEPTERS IN ZNSE

The structural and electronic-properties of substitutional phosphorus and nitrogen impurities in ZnSe are studied using pseudopotential total-energy calculations. Substitutional phosphorus and nitrogen, in their neutral states, form shallow accepters. In the case of phosphorus, the symmetry is lowered from T-d to C-3 upsilon by a Jahn-Teller distortion, and the hole is more localized on the phosphorus site. For nitrogen, however, the Jahn-Teller distortion is so small that the symmetry is approximately T-d, and the hole density is spread around nearby selenium-atom sites. For nitrogen in the positive charge state, two minimal-energy configurations are predicted: a stable state with approximately T-d symmetry and a metastable. state with C-3 upsilon symmetry, which is 0.3 eV higher in energy than the stable one.