Wurtzite ZnBeMgO films with high magnesium content were deposited by the pulsed laser deposition method at various oxygen partial pressures. Results show that the crystallinity and the band gap of ZnBeMgO films were strongly influenced by the oxygen partial pressure. With the increase of the oxygen pressure, the crystalline structure of ZnBeMgO films changed from cubic rock-salt to hexagonal wurtzite. The steady decrease in the bandgap of ZnBeMgO films from 4.71 to 4.50 eV was observed when the oxygen partial pressure increased from 2 x 10(-4) to 2 Pa. (C) 2009 Elsevier B.V. All rights reserved.