Step‐climbing Epitaxy of Layered Materials with Giant Out‐of‐plane Lattice Mismatch
Step‐climbing Epitaxy of Layered Materials with Giant Out‐of‐plane Lattice Mismatch
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具有巨大面外晶格失配的层状材料的阶梯攀爬外延
DOI：
10.1002/adma.202202754
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
Hailin Peng
中科院分区：
文献类型：
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作者：
Xuehan Zhou;Yan Liang;Huixia Fu;Ruixue Zhu;Jingyue Wang;Xuzhong Cong;Congwei Tan;Congcong Zhang;Yichi Zhang;Yani Wang;Qijia Xu;Peng Gao;Hailin Peng
大失配异质外延是高质量外延薄膜生长的一大挑战。尽管人们在平面内晶格失配的外延薄膜生长方面做了大量的工作，但在具有巨大的平面外晶格失配的阶梯衬底上外延二维层状晶体的报道却很少。本文以二维半导体Bi 2 O2 Se在三维SrTiO 3衬底上的分子束外延为例，提出了一种爬台阶外延生长策略，即第n层（n = 1，2，3.）外延层爬上与面外晶格失配有高度差的台阶，继续生长第n+1层外延层。爬台阶外延可以自发地弛豫和释放面外晶格失配引起的应变，保证了大面积外延薄膜的高质量。采用阶梯外延法可以获得厚度可控的二维Bi 2 O2 Se单晶薄膜。最值得注意的是，一个单元电池的Bi 2 O2 Se薄膜（1.2 nm厚）在室温下表现出180 cm 2/Vs的高霍尔迁移率，这超过了硅和其他具有可比厚度的二维半导体。由于在层状材料的外延中通常存在面外晶格失配，因此阶梯攀爬外延策略扩展了现有的外延生长理论，并为层状材料的高质量合成提供了指导。本文受版权保护。All rights reserved.
Heteroepitaxy with large lattice mismatch remains a great challenge for high-quality epifilm growth. Although great efforts have been devoted to epifilm growth with an in-plane lattice mismatch, the epitaxy of two-dimensional (2D) layered crystals on stepped substrates with a giant out-of-plane lattice mismatch is seldom reported. Here, taking the molecular beam epitaxy of 2D semiconducting Bi2 O2 Se on three-dimensional SrTiO3 substrates as an example, we propose a step-climbing epitaxy growth strategy, in which the nth (n = 1, 2, 3…) epilayer climbs the step with height difference from out-of-plane lattice mismatch and continues to grow the n+1th epilayer. Step-climbing epitaxy can spontaneously relax and release the strain from the out-of-plane lattice mismatch, which ensures the high quality of large-area epitaxial films. Wafer-scale uniform 2D Bi2 O2 Se single-crystal films with controllable thickness can be obtained via step-climbing epitaxy. Most notably, one-unit-cell Bi2 O2 Se films (1.2 nm thick) exhibit a high Hall mobility of 180 cm2 /Vs at room temperature, which exceeds that of silicon and other 2D semiconductors with comparable thickness. As an out-of-plane lattice mismatch is generally present in the epitaxy of layered materials, the step-climbing epitaxy strategy expands the existing epitaxial growth theory and provides guidance toward the high-quality synthesis of layered materials. This article is protected by copyright. All rights reserved.