Giant persistent photoconductivity in electron-doped SrTiO3 triggered by release of electron-lattice coupling

doi:10.1016/j.jmst.2025.09.004

J. Mater. Sci. Technol. ›› 2026, Vol. 256: 126-133.DOI: 10.1016/j.jmst.2025.09.004

• Research Article • Previous Articles Next Articles

Giant persistent photoconductivity in electron-doped SrTiO₃ triggered by release of electron-lattice coupling

Youngmin Kim^a,1, Bongwook Chung^b,1, Jeongdae Seo^c,1, Minwoo Jang, Kitae Eom^d,*, Hyungwoo Lee^a,e,*

^aDepartment of Energy Systems Research, Ajou University, Suwon 16499, Republic of Korea;
^bSchool of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea;
^cAjou Energy Science Research Center, Ajou University, Suwon 16499, Republic of Korea;
^dDepartment of Semiconducting Engineering, Gachon University, Seongnam 13120, Republic of Korea;
^eDepartment of Physics, Ajou University, Suwon 16499, Republic of Korea

Received:2025-05-20 Revised:2025-08-22 Accepted:2025-09-04 Published:2026-06-10 Online:2025-09-10
Contact: ^*E-mail addresses: keom@gachon.ac.kr (K. Eom), hyungwoo@ajou.ac.kr (H. Lee)
About author:¹These authors contributed equally to this work.

Abstract

Abstract: Strontium titanate has emerged as a promising material for oxide-based electronics due to its versatile electronic properties and compatibility with cation doping. This study investigates the giant persistent photoconductivity (PPC) in ultrathin La-doped SrTiO₃ (La:STO) films. We demonstrate that, unlike conventional PPC mechanisms based on oxygen vacancies, a strong and robust PPC can be triggered by activating electrons localized at Ti ions near the surface of La:STO films, where electron-lattice coupling plays a pivotal role. Specifically, for the 8-unit-cell-thick La:STO films, the Ti-related PPC of 1276 % is achieved under exposure to ultraviolet (UV) light with a wavelength of 405 nm. This PPC state remains highly stable, with full release taking >24 h at room temperature. Our first-principles density functional theory calculations and thickness-dependent photocurrent analysis consistently reveal that this giant PPC originates from electrons activated at Ti³⁺O₆ octahedra located near the surface of the La:STO layer. These results demonstrate that electron-lattice interactions in transition metal oxides can give rise to strong PPC characteristics, suggesting future applications in low-dimensional optoelectronic devices.

Key words: Persistent photoconductivity, La-doped SrTiO₃, Electron localizations, Electron-lattice coupling, Oxide heterostructures, SrTiO₃ thin films

Youngmin Kim, Bongwook Chung, Jeongdae Seo, Minwoo Jang, Kitae Eom, Hyungwoo Lee. Giant persistent photoconductivity in electron-doped SrTiO₃ triggered by release of electron-lattice coupling[J]. J. Mater. Sci. Technol., 2026, 256: 126-133.

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Giant persistent photoconductivity in electron-doped SrTiO₃ triggered by release of electron-lattice coupling

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