ABSTRACT
The vertical gradient freeze or valence band techniques were applied by Z. Galazka et al. to grow bulk ZnGa2O4, MgGa2O4, and mixed (Zn,Mg)Ga2O4 single crystals. X-ray fluoroscence measurements of ZnGa2O4 crystal samples when grown at optimum conditions also showed substantially stoichiometric composition for colorless and light blue/blue crystals; however, there was a small deviation from stoichiometry for dark-blue crystals. ZnGa2O4 is the most unstable compound among other Ga-based spinels, and losses of Zn(g) are much higher as compared with Ga2O(g) losses. The most intensively studied spinel in terms of luminescence is ZnGa2O4, as it was found as an efficient phosphor. The photoluminescence (PL) spectra of Mn-doped bulk ZnGa2O4 single crystals grown by the LHPG showed a peak at about 505 nm under 266 nm excitation. The PL spectra of undoped ZnGa2O4 thin films under UV excitation are generally similar to the CL spectra.
