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

Abstract

Heteroepitaxial ZnGa 2 O 4 thin films grown on sapphire substrates would be preferable for fundamental studies on properties of this material for device applications. To achieve near‐stoichiometric ZnGa 2 O 4 epitaxial thin films by pulsed laser deposition (PLD), the severe loss of Zn must be overcome. Herein, the fabrication and characterization of epitaxial (111) ZnGa 2 O 4 thin films grown on (00.1) sapphire substrates by PLD using a Zn 0.97 Ga 0.03 O 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 ZnGa 2 O 4 film. The in‐plane orientation relationship is identified to be ZnGa 2 O 4 //[11.0] Al 2 O 3 . A 14.2 nm thick (111) ZnGa 2 O 4 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.