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Ga₂O₃ is an emerging wide-band-gap semiconductor that exhibits diverse phases with varying electronic properties. ε-Ga₂O₃, a metastable polymorph, has recently been reported to be a ferroelectric semiconductor with potential application in power and high-frequency electronics [1]. Although there have been numerous attempts to grow ε-Ga₂O₃ on various substrates, single-phase ε-Ga₂O₃ thin films have not been reported. An investigation of the stability of the surface of a, b, and e polymorphs of Ga₂O₃ can facilitate the synthesis of phase-pure thin films. Results of first-principles calculations of the surface stability of the three Ga₂O₃ polymorphs as a function of the chemical potential along with their electronic properties will be presented. The stability of its (001) polar surface of Ga₂O₃ as a function of polarization and thickness will be presented. Moreover, electronic structure calculations indicate a lack of quantum confinement in α-Ga₂O₃ thin-films. Finally, different substrate effects on the stability of the three Ga₂O₃ polymorphs will be talked.
[1] S. B. Cho and R. Mishra, Applied Physics Letters 112, 162101 (2018).