中国物理B ›› 2021, Vol. 30 ›› Issue (1): 17301-.doi: 10.1088/1674-1056/abc54c

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  • 收稿日期:2020-09-17 修回日期:2020-09-17 接受日期:2020-10-28 出版日期:2020-12-17 发布日期:2020-12-23

Electric gating of the multichannel conduction in LaAlO3/SrTiO3 superlattices

Shao-Jin Qi(齐少锦)1,2,†, Xuan Sun(孙璇)1,†, Xi Yan(严曦)1,2, Hui Zhang(张慧)1,2, Hong-Rui Zhang(张洪瑞)1,2, Jin-E Zhang(张金娥)1,2, Hai-Lin Huang(黄海林)1,2, Fu-Rong Han(韩福荣)1,2, Jing-Hua Song(宋京华)1,2, Bao-Gen Shen(沈保根)1,2, and Yuan-Sha Chen(陈沅沙)1,2,‡   

  1. 1 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; 2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-09-17 Revised:2020-09-17 Accepted:2020-10-28 Online:2020-12-17 Published:2020-12-23
  • Contact: These authors contributed to this work equally. Corresponding author. E-mail: yschen@aphy.iphy.ac.cn
  • Supported by:
    Project supported by the National Basic Research Program of China (Grant Nos. 2016YFA0300701, 2017YFA0206300, 2017YFA0303601, and 2018YFA0305704), the National Natural Science Foundation of China (Grant Nos. 11520101002, 51590880, 11674378, 11934016, and 51972335), and the Key Program of the Chinese Academy of Sciences.

Abstract: The electric gating on the transport properties of two-dimensional electron gas (2DEG) at the interface of LaAlO3/SrTiO3 (LAO/STO) heterostructure has attracted great research interest due to its potential application in field-effect devices. Most of previous works of gate effect were focused on the LAO/STO heterostructure containing only one conductive interface. Here, we systematically investigated the gate effect on high-quality LAO/STO superlattices (SLs) fabricated on the TiO2-terminated (001) STO substrates. In addition to the good metallicity of all SLs, we found that there are two types of charge carriers, the majority carriers and the minority carriers, coexisting in the SLs. The sheet resistance of the SLs with a fixed thickness of the LAO layer increases monotonically as the thickness of the STO layer increases. This is derived from the dependence of the minority carrier density on the thickness of STO. Unlike the LAO/STO heterostructure in which minority and majority carriers are simultaneously modulated by the gate effect, the minority carriers in the SLs can be tuned more significantly by the electric gating while the density of majority carriers is almost invariable. Thus, we consider that the minority carriers may mainly exist in the first interface near the STO substrate that is more sensitive to the back-gate voltage, and the majority carriers exist in the post-deposited STO layers. The SL structure provides the space separation for the multichannel conduction in the 2DEG, which opens an avenue for the design of field-effect devices based on LAO/STO heterostructure.

Key words: superlattices, gate effect, minority carriers, majority carriers

中图分类号:  (Superlattices)

  • 73.21.Cd
73.40.-c (Electronic transport in interface structures) 73.20.-r (Electron states at surfaces and interfaces)