Electron paramagnetic resonance and optical spectroscopy of Er-doped β-Ga2O3

Conducting beta-Ga2O3 single crystals doped with Er3+ were grown using the floating zone method. Electron paramagnetic resonance (EPR) showed that conduction electrons can coexist with the Er3+ dopant. Optical and EPR characterizations of samples nominally doped with 0.5% and 1.5% were performed at low temperature showing that erbium substitution into beta-Ga2O3 can only be achieved effectively at the lower concentration because of the appearance of an erbium gallium garnet phase when the erbium concentration is increased. Despite the existence of two cationic sites in beta-Ga2O3, EPR measurements demonstrate that Er incorporation occurs at a single crystallographic position. Optical spectroscopy of 0.5% doped samples of the 1.5 mu m transition allowed us to determine some crystal field levels of the I-4(15/2) and I-4(13/2) multiplets. A lifetime of about 12 ms was found for the 1.5 mu m emission, indicating a high quantum yield for the I-4(13/2) multiplet. (C) 2008 American Institute of Physics.