Crystal Structure and Ferroelectric Properties of ε-Ga2O3 Films Grown on (0001)-Sapphire
Crystal Structure and Ferroelectric Properties of ε-Ga2O3 Films Grown on (0001)-Sapphire
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DOI：
10.1021/acs.inorgchem.6b02244
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发表时间：
2016-11-21
影响因子：
4.6
通讯作者：
Fornari, Roberto
中科院分区：
文献类型：
--
作者：
Mezzadri, Francesco;Calestani, Gianluca;Fornari, Roberto
采用单晶X射线衍射和动态磁滞测量技术研究了(0001)蓝宝石上低温MOCVD沉积的ε-Ga2O3的晶体结构和铁电性能。对这种相对未知的 Ga2O3 多晶型物的彻底研究表明，它是由八面体和四面体配位的 Ga3+ 位点层组成，这些位点被占据的概率为 66%。非中心对称空间群 P6(3)mc 中晶体结构的细化指出存在未补偿的电偶极子，表明铁电特性，最终通过铁电磁滞的独立测量证明了这一点。在c取向蓝宝石衬底上观察到清晰的外延关系，Ga2O3[10-10]方向与Al2O3方向[11-20]平行，产生约4.1%的晶格失配。
The crystal structure and ferroelectric properties of epsilon-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 P6(3)mc 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%.