Heteroepitaxial (111) ZnGa2O4 Thin Films Grown on (00.1) Sapphire by Pulsed Laser Deposition

Abstract

Heteroepitaxial ZnGa2O4 thin films grown on sapphire substrates would be preferable for fundamental studies on properties of this material for device applications. To achieve near‐stoichiometric ZnGa2O4 epitaxial thin films by pulsed laser deposition (PLD), the severe loss of Zn must be overcome. Herein, the fabrication and characterization of epitaxial (111) ZnGa2O4 thin films grown on (00.1) sapphire substrates by PLD using a Zn0.97Ga0.03O target are reported. A deposition temperature of 750 °C and a laser fluence of 3.5 J cm−2 are suitable for growing near‐stoichiometric ZnGa2O4 film. The in‐plane orientation relationship is identified to be [1⎯⎯1⎯⎯2] ZnGa2O4//[11.0] Al2O3. A 14.2 nm thick (111) ZnGa2O4 epitaxial thin film with a Zn/Ga atomic ratio of about 0.47 shows a narrow full width at half maximum value for the rocking curve of 0.1° and a direct optical bandgap of 4.9 eV. (© 2020 Wiley)