Bandgap engineering of sol-gel synthesized amorphous Zn 1-xMgxO films

Abstract

Amorphous Zn1-xMgxO (α-Zn1-xMg xO) ternary alloy thin films across the full compositional range were synthesized by a low-cost sol-gel method on quartz substrates. The amorphous property of the α-Zn1-xMgxO films was verified by x-ray diffraction, and atomic force microscopy revealed a smooth surface with sub-nanometer root-mean square roughness. The current phase segregation issue limiting application of crystalline Zn1-xMgxO with 38% < x < 75% was completely eliminated by growing amorphous films. Optical transmission measurements showed high transmissivity of more than 90% in the visible and near infrared regions, with optical bandgap tunability from 3.3 eV to more than 6.5 eV by varying the Mg content. © 2011 American Institute of Physics.