Bond Dipole-Based Geometric Theory of Band Alignment-

Non-Quantum Physics in the Microscopic World

报告人

Prof. Shengbai Zhang (张绳百)

School of Physical Sciences, 

USTC

时间

2025年9月23日（星期二）下午4：00

地点

物质科学教研楼B902会议室

Prof. Shengbai Zhang received his B. S. degree in electronic engineering from Jilin University in 1982 and his Ph. D. degree in Physics from the University of California at Berkeley in 1989 under Marvin L. Cohen. He moved to Xerox PARC as a postdoc, before joining the National Renewable Energy Laboratory in 1991. In 2008, he became the Senior Kodosky Constellation Chair Professor and Professor in Physics at Rensselaer Polytechnic Institute. His research involves first-principles calculations, theory, and modeling of structural and electronic properties of condensed matter by using the petaflop computational facilities at RPI’s Center for Computational Innovations (CCI).

报告摘要

Study of band alignment is plagued by the lack of a common reference for periodic systems. Typically, average potential is used as the reference for bulk calculation, but it carries no information between different systems. One may truncate a bulk to expose the vacuum level [1]. However, with respect to such a level, the average potential is strongly orientation dependent [2]. This happens because the average potential is a projection of a shape-dependent bulk quadrupole tensor in the given direction [3]. By introducing Wigner-Seitz atoms (WSA), which are charge neutral, maintain local crystal symmetry, and tessellate space, one can however reduce the tensor to the expected scalar quantity, whereby setting the stage for a universal and intrinsic band alignment [4]. The WSA approach further allows for an evaluation from classical electrostatics of the charge transfer at interface, which manifests itself as the formation of (sometimes sizable) interfacial bond dipoles. Therefore, band alignment is not a pure bulk property, as widely believed. Rather, it, in general, consists of two parts: (1) intrinsic contribution of bulk and (2) extrinsic contribution due to interfacial bond polarization. We discover that for interface between isotropic systems, the potential shift due to interface charge transfer is only a function of bulk crystal structure and, as such, strictly interface orientation independent in line with experiments [4]. More impressively, our seemingly simple classical treatment of the band alignment yields results of density functional theory accuracy for interfaces between 29 diverse isotropic and anisotropic systems of various crystal structures.

References

1. D.-H. Choe, D. West, S. Zhang, Phys. Rev. Lett. 121, 196802 (2018).

2. L. Kleinman, Phys. Rev. B 24, 7412 (1981).

3. D.-H. Choe, D. West, S. Zhang, Phys. Rev. B 103, 235202 (2021).

4. Z. Jiang, D. West, and S. Zhang, Featured Article, Appl. Phys. Rev. 12, 011411 (2025).