High-: κ dielectric ϵ-Ga₂O₃ stabilized in a transparent heteroepitaxial structure grown by mist CVD at atmospheric pressure

The dielectric constant of metastable ϵ-Ga₂O₃ was evaluated for the first time by using a transparent heteroepitaxial structure of ϵ-Ga₂O₃/indium tin oxide/yttria-stabilized zirconia. The dielectric ϵ-Ga₂O₃ layer was grown by the facile solution route of mist chemical vapor deposition at atmospheric pressure. The highest dielectric constant of nearly 32 (at an AC frequency of 10 kHz) was about three times larger than that of the most stable β-Ga₂O₃ phase. This high dielectric constant is attributed to the polar structure of ϵ-Ga₂O₃ unlike β-Ga₂O₃, and is comparable to those of the so-called high-κ dielectric oxides. The combination of a wide bandgap and a high dielectric constant would be beneficial for the future development of optoelectrical devices.