Photoluminescence from CdGa and HgGa acceptors in GaN

Photoluminescence from GaN implanted with Cd or Hg ions was studied and compared with first-principles calculations. In Cd-implanted GaN, the blue band (BLCd) with a maximum at 2.7 eV is attributed to the CdGa acceptor with an ionization energy of 0.55 eV. In Hg-implanted GaN, the green band (GLHg) with a maximum at 2.44 eV is attributed to the HgGa acceptor with an ionization energy of 0.77 eV. The shapes of the BLCd and GLHg bands are asymmetric, with a similar Franck–Condon shift of about 0.28 eV. The electron- and hole-capture coefficients for the CdGa and HgGa acceptors are found. The experimentally found parameters agree reasonably well with first-principles calculations using HSE hybrid functional satisfying the generalized Koopmans' theorem.