Structural, microstructural, and optical properties of Zn1−x Mg x O thin films grown onto glass substrate by ultrasonic spray pyrolysis

Abstract

Pure and doped Zn1−x Mg x O films were deposited onto glass substrate by ultrasonic spray pyrolysis technique. The variation of lattice constant and the blue shift of near-band-edge emission indicate that Zn2+ ions are successfully substituted by Mg2+ ions within ZnO lattice. At higher Mg content (x ≥ 0.21), a drastic change appears in the morphology, as a result of structural changes from wurtzite (ZnO) structure into a mixture of wurtzite and cubic (MgO) phases. FTIR study indicated the existence of distinct characteristic absorption peaks at ~442 cm−1 for Zn–O stretching mode that shifted toward the red region with the increase in Mg content. In addition to the host phonons of ZnO, one additional band was observed around 523 cm−1, presumably attributed to the Mg-related vibrational mode. The optical constants and thickness of thin films have been determined using experimental transmittance data. The luminescence intensity at 2.63 eV of Zn0.85Mg0.15O thin films was found to be approximately 13 times higher than that of pure ZnO film measured under the same excitation conditions.