纤锌矿结构ZnO、AlN、GaN自发极化及压电系数的第一性原理计算

First-principles study of spontaneous polarization and piezoelectric constants of wurtzite ZnO,AlN and GaN

以现代极化理论为基础,通过构建一种结构简单、直观的计算模型,分别采用Berry phase和最大局域化Wannier函数方法并结合第一性原理,计算了纤锌矿结构的ZnO、AlN及GaN半导体的自发极化及压电系数,研究了自发极化与晶体结构之间的关系.计算结果与已有报道结果吻合较好.结果表明:AlN的自发极化及压电系数在三种半导体中最大,其自发极化超过另外两种半导体的两倍.发现最大局域化Wannier函数方法与Berry phase方法相比,由于产生了Wannier中心,因此在分析自发极化、电子结构及原子成键上具有独特的优势,能给出更清晰的物理图像.

Based on the modern polarization theory and first-principles calculation, the spontane- ous polarization and piezoelectric constants of wurtzite ZnO, A1N and GaN are calculated by using the Berry phase method and maximally localized Wannier functions, respectively. The relations between spontaneous polarization and crystal structures are also investigated. The numerical re- sults coincide with the previous reports, indicate that the spontaneous polarization and piezoelec- tric constants of AIN are the largest one among the three semiconductors. The spontaneous polar- ization of A1N is two times more than the other two. Comparing with the Berry phase method, due to the production of Wannier centers maximally localized Wannier functions has a unique ad- vantage in analysing spontaneous polarization, electric structures and atomic bonding, which will give a more clear physical picture.