MOCVD of pure and Ga-doped epitaxial ZnO

The films on (111) ZrO2(Y 2O3), (111) SrTiO3, are characterized by a higher epitaxial quality than films on sapphire traditionally used for ZnO epitaxy. This results in the higher solubility of Ga2O3 in ZnO films on (111) ZrO2(Y 2O3) (at least up to 7.5 at.% Ga in the sum of Ga and Zn) as compared to the films on r-Al2O3 (below 3 at.% Ga) due to the epitaxial stabilization. The intensity of the UV photoluminescence (PL) correlates with the epitaxial quality of ZnO films. Ga-doping resulted in the quenching of green PL band because of Ga3+ occupancy of the octahedral interstitials in the ZnO structure (in agreement with the variation of the ZnO(Ga2O3) lattice parameters).