TY - JOUR
T1 - Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics
AU - Lewin, Martin
AU - Baeumer, Christoph
AU - Gunkel, Felix
AU - Schwedt, Alexander
AU - Gaussmann, Fabian
AU - Wueppen, Jochen
AU - Meuffels, Paul
AU - Jungbluth, Bernd
AU - Mayer, Joachim
AU - Dittmann, Regina
AU - Waser, Rainer
AU - Taubner, Thomas
N1 - Funding Information:
The authors thank Lena Jung, Christian Rodenbücher, Alexander von Hoegen, and Friedemann Landmesser for helpful discussions and Daliborka Erdoglija for the preparation of the gold patches. Funding from the DFG (German Science Foundation) within the collaborative research center SFB 917 “Nanoswitches” is gratefully acknowledged. F.G. thanks the DFG for financial support within project GU1604. Furthermore, this work was financially supported by the Ministry of Innovation, Science, Research and Technology of the German State of North Rhine-Westphalia.
Funding Information:
The authors thank Lena Jung, Christian Rodenb?cher, Alexander von Hoegen, and Friedemann Landmesser for helpful discussions and Daliborka Erdoglija for the preparation of the gold patches. Funding from the DFG (German Science Foundation) within the collaborative research center SFB 917 ?Nanoswitches? is gratefully acknowledged. F.G. thanks the DFG for financial support within project GU1604. Furthermore, this work was financially supported by the Ministry of Innovation, Science, Research and Technology of the German State of North Rhine-Westphalia.
Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/10/17
Y1 - 2018/10/17
N2 - 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 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.
AB - 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 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.
KW - ceramics
KW - grain boundary
KW - infrared spectroscopy
KW - near-field optical microscopy
KW - strontium titanate
UR - http://www.scopus.com/inward/record.url?scp=85052975730&partnerID=8YFLogxK
U2 - 10.1002/adfm.201802834
DO - 10.1002/adfm.201802834
M3 - Article
AN - SCOPUS:85052975730
VL - 28
JO - Advanced functional materials
JF - Advanced functional materials
SN - 1616-301X
IS - 42
M1 - 1802834
ER -