The effect of annealing on photoluminescence from defects in ammonothermal GaN
M. A. Reshchikov, D. O. Demchenko, D. Ye, Oleksandr Andrieiev, Mykhailo Vorobiov, Karolina Grabiańska, Marcin Zając, Przemyslaw Nita, Małgorzata Iwińska, Michał Boćkowski, Benjamin McEwen, F. Shahedipour‐Sandvik
Abstract
Ammonothermal GaN samples with the concentration of free electrons of 1018 and 1019 cm−3 were annealed in a wide range of temperatures (Tann = 300–1400 °C) under atmospheric N2 pressure and under ultra-high N2 pressure conditions to avoid the GaN decomposition. Photoluminescence (PL) studies reveal the YL2 band with a maximum at 2.3 eV before annealing and two new PL bands after annealing at Tann > 600 °C: the OL3 band with a maximum at 2.1 eV and the RL4 band with a maximum at 1.6–1.7 eV. The ammonothermal GaN samples have high concentrations of complexes containing gallium vacancy (VGa), hydrogen, and oxygen. The first-principles calculations suggest that the VGa-3Hi complex is the origin of the YL2 band, while the VGa-3ON complex is responsible for the RL4 band.