Among the novel materials for electronic applications and novel device concepts beyond classical Si‐based CMOS technology, SrTiO₃ represents a prototype role model for functional oxide materials: It enables resistive switching, but can also form a 2D electron gas at its interface and thus enables tunable transistors. However, the interplay between charge carriers and defects in SrTiO₃ is still under debate. Infrared spectroscopy offers the possibility to characterize structural and electronic properties of SrTiO₃ in operando, but is hampered by the diffraction‐limited resolution. To overcome this limitation and obtain nanoscale IR spectra of donor‐doped Sr_1‐xLa_xTiO₃ ceramics, scattering‐type scanning near‐field optical microscopy is applied. By exploiting plasmon–phonon coupling, the local electronic properties of doped SrTiO₃ are quantified from a detailed spectroscopic analysis in the spectral range of the near‐field ‘phonon resonance’. Single crystal‐like mobility, an increase in charge carrier density N and an increase in ε_∞ at grain boundaries (µ≈ 5.7 cm² V⁻¹s⁻¹, N = 7.1 × 10¹⁹ cm⁻³, and ε_∞ = 7.7) and local defects (µ≈ 5.4 cm² V⁻¹s⁻¹, N = 1.3 × 10²⁰ cm⁻³, and ε_∞ = 8.8) are found. In future, subsurface quantification of defects and free charge carriers at interfaces and filaments in SrTiO₃ can be envisioned.

中文翻译：

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红外声子共振的纳米光谱技术能够对SrTiO3掺杂陶瓷的电子性能进行局部量化

在电子应用的新型材料和经典的基于Si的CMOS技术之外的新型器件概念中，SrTiO ₃代表了功能性氧化物材料的原型角色模型：它可以进行电阻切换，但也可以在其界面处形成二维电子气，从而实现可调晶体管。然而，电荷载体与SrTiO _3中的缺陷之间的相互作用仍在争论中。红外光谱法可用于表征SrTiO _3的结构和电子性质，但受衍射极限分辨率的影响。为了克服此限制并获得施主掺杂的Sr _1-x La _x TiO _3的纳米级红外光谱陶瓷，应用散射型扫描近场光学显微镜。通过利用等离振子-声子耦合，可以在近场“声子共振”的光谱范围内通过详细的光谱分析对掺杂的SrTiO ₃的局部电子性质进行量化。单晶样的流动性，增加载流子密度Ñ和增加ε _∞在晶界（μ听，说： 5.7厘米² V ^-1小号^-1，Ñ = 7.1×10 ¹⁹厘米^-3，和ε _∞ = 7.7 ）和局部缺陷（μ听，说： 5.4厘米² V ^-1小号^-1，Ñ = 1.3×10 ²⁰厘米^-3，和ε _∞ = 8.8）中找到。将来，可以设想SrTiO ₃中界面和细丝处的缺陷和自由电荷载子的地下定量。