Origin of efficient luminescence from GaN:Eu3+ epitaxial films revealed by microscopic photoluminescence imaging spectroscopy

We have studied photoluminescence (PL) properties of Eu3+-doped GaN (GaN:Eu3+) epitaxial films by microscopic PL imaging spectroscopy. The GaN:Eu3+ epitaxial films exhibit efficient red luminescence related to intra-4f transitions of Eu3+ ions. The intensity and the spectral shape of the Eu3+-related PL are sensitive to the Eu3+ concentration, the excitation wavelength, and the monitored position. Microscopic PL imaging spectroscopy revealed that efficient red luminescence of GaN:Eu3+ epitaxial films is due to Eu3+ ions around point defects and dislocations.