Control of Al composition of mist chemical vapor deposition grown α-(AlGa)2O3 alloy thin films by acetylacetonation of Al ion

Abstract

Abstract We investigated the dominant factors affecting the Al composition of α-(AlGa)2O3 alloy thin films in mist CVD, focusing on the acetylacetonation of the source solutions. The Al–acetylacetonate (acac) complex formation time was evaluated using Fourier-transform IR spectroscopy to examine the effectiveness of heating during stirring of the source solutions. Then, α-(AlGa)2O3 alloy thin films were grown in source solutions in which the state of the acac complex was changed by adding ammonia water and/or hydrochloric acid, and the Al composition increased with increasing the pH value due to the acceleration of acetylacetonation. The growth-temperature dependence of the Al composition was also experimentally investigated. The Al composition decreased with increasing growth temperature. The reasons are due to the strength of the Al–O bond or the dissociation of the Al–acac ligand.