Crystal Structure and Ferroelectric Properties of ε-Ga 2 O 3 Films Grown on (0001)-Sapphire
2016; American Chemical Society; Volume: 55; Issue: 22 Linguagem: Inglês
10.1021/acs.inorgchem.6b02244
ISSN1520-510X
AutoresFrancesco Mezzadri, G. Calestani, Francesco Boschi, Davide Delmonte, Matteo Bosi, R. Fornari,
Tópico(s)ZnO doping and properties
ResumoThe crystal structure and ferroelectric properties of ε-Ga2O3 deposited by low-temperature MOCVD on (0001)-sapphire were investigated by single-crystal X-ray diffraction and the dynamic hysteresis measurement technique. A thorough investigation of this relatively unknown polymorph of Ga2O3 showed that it is composed of layers of both octahedrally and tetrahedrally coordinated Ga3+ sites, which appear to be occupied with a 66% probability. The refinement of the crystal structure in the noncentrosymmetric space group P63mc pointed out the presence of uncompensated electrical dipoles suggesting ferroelectric properties, which were finally demonstrated by independent measurements of the ferroelectric hysteresis. A clear epitaxial relation is observed with respect to the c-oriented sapphire substrate, with the Ga2O3 [10–10] direction being parallel to the Al2O3 direction [11–20], yielding a lattice mismatch of about 4.1%.
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