Formation of γ-Ga2O3 by ion implantation: Polymorphic phase transformation of β-Ga2O3

Ion implantation induced phase transformation and the crystal structure of a series of ion implanted beta-Ga2O3 samples were studied using electron diffraction, high resolution transmission electron microscopy, and scanning transmission electron microscopy. In contrast to previous reports suggesting an ion implantation induced transformation to the orthorhombic kappa-phase, we show that for Si-28(+), Ni-58(+), and stoichiometric Ga-69(+)/O-16(+)-implantations, the monoclinic beta-phase transforms to the cubic gamma-phase. The gamma-phase was confirmed for implantations over a range of fluences from 10(14) to 10(16) ions/cm(2), indicating that the transformation is a general phenomenon for beta-Ga2O3 due to strain accumulation and/or gamma-Ga2O3 being energetically preferred over highly defective beta-Ga2O3. Published under an exclusive license by AIP Publishing.