Structural, Optical, and Electrical Characteristics of Metastable κ-phase Ga₂O₃ Grown by Metal-Organic Chemical Vapor Deposition Using H₂O as an Oxygen Precursor

We report on the structural, optical, and electrical characteristics of metastable -Ga 2 O 3 epitaxially grown on a -plane sapphire substrate by a metal organic chemical vapor deposition system using H 2 O as an oxygen precursor.The effects of key epitaxial growth parameters such as group III molar flow rate, H 2 O vapor flow rate, and types of carrier gas were systematically studied by x-ray diffraction, atomic force microscopy, and photoluminescence measurements.The group III molar flow rate was shown to strongly affect the growth rate and root mean square roughness.On the other hand, the H 2 O flow rate was found to be a critical factor for uniform surface coverage.Furthermore, we show that growth using N 2 as a carrier gas, instead of conventional H 2 carrier gas, can lead to higher Hall electron mobility, which was measured after post-growth annealing.