Formation energy of optically active Er3+ centers in Er doped GaN

Erbium doped GaN (GaN:Er) and low In-content InxGa1-xN (x similar to 0.05) epilayers were synthesized by metal organic chemical deposition. The 1.54 mu m PL emission intensity was monitored for GaN:Er epilayers grown at different growth temperatures and utilized to establish a value of 1.8 +/- 0.2 eV for the formation energy (E-F) of the optically active Er3+ centers in GaN. The optically active Er+ centers are presumably Er and nitrogen vacancy (Er-V-N) complexes. The experimentally measured value of the E-F of the optically active Er3+ centers is about 0.98 eV larger than the calculated formation energy of Er ions at Ga sites; however, it is 1.1-2.2 eV lower than the formation energy of V-N in GaN. Due to the large E-F values, relatively high growth temperatures are required to improve the 1.54 mu m emission efficiency in GaN:Er. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742196]