Atomic-scale origin of two-dimensional electron gas and two-dimensional hole gas in SrTiO₃/LaAlO₃/SrTiO₃ heterostructures

Song Haili; Huang Rong

doi:10.11714/acta.snus.ZR20260107

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Atomic-scale origin of two-dimensional electron gas and two-dimensional hole gas in SrTiO₃/LaAlO₃/SrTiO₃ heterostructures

更新时间：2026-07-13

- Atomic-scale origin of two-dimensional electron gas and two-dimensional hole gas in SrTiO₃/LaAlO₃/SrTiO₃ heterostructures
- Acta Scientiarum Naturalium Universitatis Sunyatseni Pages: 1-6(2026)
- 作者机构：
  
  1.生物无机与合成化学教育部重点实验室 / 中山大学化学学院，广东广州510006
  2.云南大学材料与能源学院 / 电镜中心，云南昆明 650091
- 作者简介：
- 基金信息：
- DOI：10.11714/acta.snus.ZR20260107
  CLC： O73;O766
- Received：21 April 2026，
  
  Revised：2026-06-01，
  
  Accepted：05 June 2026，
  
  Online First：2026-06，
- 稿件说明：
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Song Haili, Huang Rong. Atomic-scale origin of two-dimensional electron gas and two-dimensional hole gas in SrTiO₃/LaAlO₃/SrTiO₃ heterostructures[J/OL]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2026, 1-6.
DOI：

Song Haili, Huang Rong. Atomic-scale origin of two-dimensional electron gas and two-dimensional hole gas in SrTiO₃/LaAlO₃/SrTiO₃ heterostructures[J/OL]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2026, 1-6. DOI： 10.11714/acta.snus.ZR20260107.

摘要

通过脉冲激光沉积技术在SrTiO₃（001）衬底上制备了SrTiO

/LaAlO₃/SrTiO

（衬底）三明治异质结构。原子尺度结构表征显示，n型界面（SrTiO

衬底/LaAlO₃）附近存在梯度La元素扩散，界面附近部分Ti

被还原为Ti

，载流子浓度约为4.98×10¹³ cm

-2

。类铁电离子位移极化矢量分析表明，两个界面均为尾对头配置：SrTiO

类铁电极化指向界面，LaAlO₃类铁电极化背离界面，且LaAlO₃类铁电极化强度远大于SrTiO

。n型界面处，尾对头类铁电极化产生的净负束缚电荷部分抵消了极性不连续驱动的电子积累，使实测载流子浓度较极化崩塌模型理论值低约一个数量级。p型界面处，LaAlO₃类铁电极化产生的净负束缚电荷与p型极性不连续对空穴的需求协同驱动二维空穴气形成。本研究揭示了薄膜内部晶格畸变导致的类铁电离子位移极化分布对双界面导电行为的调制机制。

Abstract

SrTiO₃/LaAlO₃/SrTiO₃ （substrate） sandwich heterostructures were grown on SrTiO₃ （001） substrates by pulsed laser deposition. Atomic-scale structural characterization reveals gradient La diffusion near the n-type interface （SrTiO₃ substrate/LaAlO₃）， accompanied by partial reduction of Ti⁴⁺ to Ti³⁺， yielding a carrier concentration of approximately 4.98×10¹³ cm⁻². Ferroelectric-like displacement polarization vector analysis demonstrates that both interfaces exhibit a tail-to-head configuration： The SrTiO₃ polarization points toward the interface， while the LaAlO₃ polarization points away from the interface， with the LaAlO₃ polarization intensity being significantly stronger than that of SrTiO₃. At the n-type interface， the net negative bound charge generated by the tail-to-head ferroelectric-like polarization partially counteracts the electron accumulation driven by the polar discontinuity， resulting in an experimental carrier concentration approximately one order of magnitude lower than the theoretical value predicted by the polar catastrophe model. At the p-type interface， the net negative bound charge arising from the LaAlO₃ ferroelectric-like polarization acts synergistically with the hole requirement of the p-type polar discontinuity to drive two-dimensional hole gas formation. This study reveals the modulation mechanism of ferroelectric-like displacement polarization distributions induced by lattice distortions within the film on the dual-interface conduction behavior.

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references

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