Cu2O 单晶 (111) 表面的原子视图：重构、电子特性和能带弯曲效应,The Journal of Physical Chemistry C

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Cu2O 单晶 (111) 表面的原子视图：重构、电子特性和能带弯曲效应
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2022-09-26 , DOI: 10.1021/acs.jpcc.2c04335
Alexander Gloystein ₁ , Jack Anthony Creed ₁ , Niklas Nilius ₁

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_{近 30 年来，Cu 2} O(111) 表面的 (√3 × √3) R 30° 重建的性质一直备受争议。这项工作表明，最近为 Cu ₂ O(111) 薄膜开发的纳米锥体重建模型也适用于大块样品。为此，天然Cu ₂ O(111) 晶体的表面采用常见的表面科学方法制备，在电子衍射中产生了稳健且可重复的(√3 × √3) R 30° 超结构图案。_{原子分辨的 STM 图像显示规则排列的三重对称突起，与其中 Cu 4}的纳米锥体模型完全一致O 单元附着在贫铜 (111) 表面的每三个 Cu-O 六元环上。STM 电导谱揭示了氧化物的 p 型特征，其价带顶部固定在费米能级上。根据尖端电场中的带弯曲效应，可确定 (√3 × √3) R 30° 相的感应载流子浓度为 6 × 10 ¹⁷ cm ^{–3 。}在覆盖有贫铜少数相的少数 (1 × 1) 斑块上，该值增加到 4 × 10 ¹⁸ cm ^–3，表明原子结构和给定表面终止的局部筛选响应之间的密切相互作用。我们的工作阐明了块状 Cu _{2的 (√3 × √3)}R 30° 重建的性质O(111) 通过将其连接到最近提出的纳米锥体重建模型。

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Atomic View on the (111) Surface of a Cu2O Single Crystal: Reconstruction, Electronic Properties, and Band-Bending Effects

The nature of the (√3 × √3)R30° reconstruction of the Cu₂O(111) surface has been heavily debated for almost 30 years. This work demonstrates that the nanopyramidal reconstruction model that was recently developed for Cu₂O(111) thin films is valid also for bulk samples. For this purpose, the surface of a natural Cu₂O(111) crystal was prepared by common surface science methods, yielding a robust and reproducible (√3 × √3)R30° superstructure pattern in electron diffraction. Atomically resolved STM images display a regular array of trifold symmetric protrusions, in perfect agreement with the nanopyramidal model in which Cu₄O units attach to every third Cu–O six-membered ring of a Cu-depleted (111) surface. STM conductance spectra reveal the p-type character of the oxide with the valence-band top pinned to the Fermi level. From band-bending effects in the tip electric field, an induced carrier concentration of 6 × 10¹⁷ cm^–3 is determined for the (√3 × √3)R30° phase. This value increases to 4 × 10¹⁸ cm^–3 on the few (1 × 1) patches covered with a Cu-poor minority phase, indicating a close interplay between atomic structure and local screening response for a given surface termination. Our work clarifies the nature of the (√3 × √3)R30° reconstruction of bulk Cu₂O(111) by connecting it to the recently proposed nanopyramidal reconstruction model.

更新日期：2022-09-26

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