TY - JOUR
T1 - Artificially Designed Compositionally Graded Sr-Doped NaTaO3Single-Crystalline Thin Films and the Dynamics of Their Photoexcited Electron-Hole Pairs
AU - Konno, Rio
AU - Maruyama, Shingo
AU - Kosaka, Takumu
AU - Katoh, Ryuzi
AU - Takahashi, Ryota
AU - Kumigashira, Hiroshi
AU - Ichikuni, Nobuyuki
AU - Onishi, Hiroshi
AU - Matsumoto, Yuji
N1 - Funding Information:
This work was partially supported by a Grant-in-Aid for Scientific Research (No.15H02021, 18KK0161, 20H02610, 20H02699) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. This work was performed with the approval of the Photon Factory Program Advisory Committee (Proposal No. 2018G078).
Publisher Copyright:
©
PY - 2021/1/12
Y1 - 2021/1/12
N2 - Sr-doped NaTaO3 (NTO) single-crystalline films with different Sr compositions of up to 20 mol %, including an NTO film, were first fabricated on LaAlO3(001) substrates by pulsed laser deposition. A gradual simultaneous increase of the lattice constants and the optical absorption edge energy was found as the doped Sr composition increased, seemingly exhibiting a structural discontinuity at a critical doping level of around 10 mol %. Extended X-ray absorption fine structure (EXAFS) analysis revealed that the doped Sr atoms were substituted for both the A and B sites, with their stoichiometric number ratio close to that previously reported for bulk Sr-doped NTO samples, resulting in the Sr-doped NTO films being still highly insulative comparable to the NTO film. Second, in spite of the well-known intrinsic nature of the high diffusivity of Sr ions in oxides, the compositionally graded Sr-doped NTO films were successfully fabricated almost as designed to have the upward and downward Sr composition gradients with a maximum doping level of 10 mol % from the substrate along the growth direction within the films. The preliminary time-resolved microwave conductivity measurement demonstrated that the lifetime of the photoexcited carriers in the compositionally graded Sr-doped NTO films was longer than in any of the NTO and homogeneous Sr-doped NTO films.
AB - Sr-doped NaTaO3 (NTO) single-crystalline films with different Sr compositions of up to 20 mol %, including an NTO film, were first fabricated on LaAlO3(001) substrates by pulsed laser deposition. A gradual simultaneous increase of the lattice constants and the optical absorption edge energy was found as the doped Sr composition increased, seemingly exhibiting a structural discontinuity at a critical doping level of around 10 mol %. Extended X-ray absorption fine structure (EXAFS) analysis revealed that the doped Sr atoms were substituted for both the A and B sites, with their stoichiometric number ratio close to that previously reported for bulk Sr-doped NTO samples, resulting in the Sr-doped NTO films being still highly insulative comparable to the NTO film. Second, in spite of the well-known intrinsic nature of the high diffusivity of Sr ions in oxides, the compositionally graded Sr-doped NTO films were successfully fabricated almost as designed to have the upward and downward Sr composition gradients with a maximum doping level of 10 mol % from the substrate along the growth direction within the films. The preliminary time-resolved microwave conductivity measurement demonstrated that the lifetime of the photoexcited carriers in the compositionally graded Sr-doped NTO films was longer than in any of the NTO and homogeneous Sr-doped NTO films.
UR - http://www.scopus.com/inward/record.url?scp=85099083801&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85099083801&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.0c03487
DO - 10.1021/acs.chemmater.0c03487
M3 - Article
AN - SCOPUS:85099083801
SN - 0897-4756
VL - 33
SP - 226
EP - 233
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 1
ER -