The electronic states of manganese in p-type GaN are investigated using photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. A series of sharp PL lines at 1.0 eV is observed in codoped GaN and attributed to the intra d-shell transition 4T 2(F)- 4T 1(F) of Mn 4+ ions. PLE spectrum of the Mn 4+ [ 4T 2(F)- 4T 1(F)] luminescence reveals intracenter excitation processes via the excited states of Mn 4+ ions. PLE peaks observed at 1.79 and 2.33 eV are attributed to the intra-d-shell 4T 1(P)- 4T 1(F) and 4A 2(F)- 4T 1 transitions of Mn 4+, respectively. In addition to the intrashell excitation processes, a broad PLE band involving charge-transfer transition of the Mn 4+/3+ deep level is observed, which is well described by the Lucovsky model. As determined from the onset of this PLE band, the position of the Mn 4+/3+ deep level is 1.11 eV above the valence band maximum, which is consistent with prior theory using ab initio calculations. Our work indicates 4+ is the predominant oxidation state of Mn ions in p-type GaN:Mn when the Fermi energy is lower than 1.11 eV above the valence band maximum.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)