带隙在极性表面和界面重构中的作用
The role of the band gaps in reconstruction of polar surfaces and interfaces
摘要：
密度泛函理论应用于一个简单的离子材料，MgO，被用来作为一个模型系统，以澄清电子驱动机制的几个方面，以补偿在极性结构中的分散的静电势。我们证明，在化学计量的自支撑膜，电子重建是有限的带隙。这在样品的主体中产生残余电场，其对板的两个表面之间的电子转移的微小偏差极其敏感。在异质结构中，带隙被一个新的有效能量标度所取代，该有效能量标度由其组分的能带排列所设定。这改变了重建路径，使得电子机制可以从尽可能小的能量尺度中受益。
英文摘要：
Density functional theory applied to a simple ionic material, MgO, is used as a model system to clarify several aspects of electronic driven mechanism to compensate for the diverging electrostatic potential in the polar structures. We demonstrate that in the stoichiometric free standing films, the electronic reconstruction is limited by the band gap. This produces a residual electric field in the bulk of the sample which is extremely sensitive to tiny deviations in electron transfer between two surfaces of the slab. In heterostructures, the band gap is replaced by a new effective energy scale set by the band alignment of its component. This changes the reconstruction pathways so that the electronic mechanism can benefit from the smallest energy scale possible.
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