Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics
Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics
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DOI：
10.1002/adfm.201802834
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发表时间：
2018-10-17
影响因子：
19
通讯作者：
Taubner, Thomas
中科院分区：
文献类型：
--
作者：
Lewin, Martin;Baeumer, Christoph;Taubner, Thomas
在电子应用的新材料和超越经典硅基CMOS技术的新器件概念中，SrTiO 3代表了功能氧化物材料的原型角色模型：它可以实现电阻开关，但也可以在其界面形成2D电子气，从而实现可调晶体管。然而，SrTiO 3中载流子和缺陷之间的相互作用仍在争论中。红外光谱提供了表征SrTiO 3的结构和电子性质的可能性，但受到衍射限制的分辨率。为了克服这一限制，并获得纳米级的施主掺杂的Sr 1-xLaxTiO 3陶瓷的红外光谱，散射型扫描近场光学显微镜应用。通过利用等离子体声子耦合，掺杂SrTiO 3的局部电子性质从一个详细的光谱分析中的近场“声子共振”的光谱范围内进行量化。类似单晶的迁移率、载流子密度N的增加和载流子浓度的增加，（无穷大）晶界处（mu约为5.7 cm（2）V（-1）s（-1），N = 7.1 x 10（19）cm（-3），（无穷大）= 7.7）和局部缺陷（mu约为5.4 cm（2）V（-1）s（-1），N = 1.3 x 10（20）cm（-3），（无穷大）= 8.8）。在未来，可以设想在SrTiO 3中的界面和细丝处的缺陷和自由电荷载流子的次表面量化。
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 Sr1-xLaxTiO3 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 epsilon(infinity) at grain boundaries (mu approximate to 5.7 cm(2) V(-1)s(-1), N = 7.1 x 10(19) cm(-3), and epsilon(infinity) = 7.7) and local defects (mu approximate to 5.4 cm(2) V(-1)s(-1), N = 1.3 x 10(20) cm(-3), and epsilon(infinity) = 8.8) are found. In future, subsurface quantification of defects and free charge carriers at interfaces and filaments in SrTiO3 can be envisioned.