Fang Le, Aggoune Wahib, Ren Wei, Draxl Claudia
State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, ICQMS and Physics Department, Shanghai University, Shanghai, 200444, China.
Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin 12489, Germany.
ACS Appl Mater Interfaces. 2023 Mar 1;15(8):11314-11323. doi: 10.1021/acsami.2c21886. Epub 2023 Feb 14.
The emerging interest in two-dimensional electron gases (2DEGs), formed at interfaces between two insulating oxide perovskites, poses a crucial fundamental question in view of future electronic devices. In the framework of density-functional theory, we investigate the possibility to control the characteristics of the 2DEG formed at the LaInO/BaSnO interface by including a ferroelectric layer. To do so, we consider BaTiO as a prototype example and examine how the orientation of the ferroelectric polarization impacts density and confinement of the 2DEG. We find that aligning the ferroelectric polarization toward (outward) the LaInO/BaSnO interface leads to an accumulation (depletion) of the interfacial 2DEG. Varying its magnitude, we find a linear effect on the 2DEG charge density that is confined within the BaSnO side. Analysis of the optimized geometries reveals that inclusion of the ferroelectric layer makes structural distortions at the LaInO/BaSnO junction less pronounced, which, in turn, enhances the 2DEG density. Thicker ferroelectric layers allow for reaching higher polarization magnitude. We discuss the mechanisms behind all these findings and rationalize how the characteristics of both 2DEGs and 2D hole gases can be controlled in the considered heterostructures. Overall, our results can be generalized to other combinations of ferroelectric, polar, and nonpolar materials.
在两种绝缘氧化物钙钛矿界面形成的二维电子气（2DEG）引发了人们新的兴趣，从未来电子器件的角度来看，这提出了一个至关重要的基本问题。在密度泛函理论框架下，我们研究了通过引入铁电层来控制在LaInO/BaSnO界面形成的2DEG特性的可能性。为此，我们以BaTiO为例进行研究，考察铁电极化方向如何影响2DEG的密度和限制情况。我们发现，使铁电极化朝向（向外）LaInO/BaSnO界面会导致界面2DEG的积累（耗尽）。改变其大小，我们发现对限制在BaSnO一侧的2DEG电荷密度有线性影响。对优化几何结构的分析表明，引入铁电层会使LaInO/BaSnO结处的结构畸变不那么明显，这反过来又提高了2DEG密度。更厚的铁电层能够达到更高的极化强度。我们讨论了所有这些发现背后的机制，并阐述了在所考虑的异质结构中如何控制2DEG和二维空穴气的特性。总体而言，我们的结果可以推广到铁电、极性和非极性材料的其他组合。
