Structural and optical properties of Zn1−xMgxO thin films synthesized with metal organic chemical vapor deposition

• DOI: 10.1007/s11664-006-0217-7
• Publication Date: 2007-04-06T22:49:08Z
• Authors: S. -H. Park; K. -B. Kim; S. -Y. Seo; S. -H. Kim; S. -W. Han
• Keywords: Wurtzite crystal structure; Absorption edge; Lattice constant

We present the structural and optical properties of Zn1−xMgxO thin films studied using x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS), and photoluminescence (PL) measurements. The Zn1−xMgxO films on sapphire [0001] substrates were fabricated with metal organic chemical vapor deposition (MOCVD). The XRD measurements showed that the Zn1−xMgxO films (x≤0.05) had a wurtzite structure without any MgO phase and were epitaxially grown along the c-axis of the Al2O3 substrate. The lattice constant of the Zn0.95Mg0.05O film shrank by 0.023 A, compared with that of ZnO crystals. From the EXAFS measurements on the Zn1−xMgxO films at Zn K-edge, we found a substantial amount of distortion in the bond length of Zn-Zn pairs with a small amount of Mg substitution on the Zn site. The PL measurements showed a gradual increment of the main exciton transitions from 3.36 eV (x=0.0) to 3.57 eV (x=0.05) at 10 K. We also observed a strong deep-level emission near 2.3 eV from the specimen with x=0.05.