Issue 31, 2024

Carrier generation and compensation mechanism in La2SnO2S3

Abstract

Some Cu-based oxychalcogenides demonstrate robust p-type conductivity, though achieving effective n-type doping in such materials remains a persistent challenge. Among oxychalcogenides, La2SnO2S3 has been proposed as a candidate for an n-type semiconductor because of its dispersive conduction band primarily derived from the Sn-5s states. The experimentally observed n-type conductivity of La2SnO2S3 is, however, limited to a low value, and the underlying atomistic and electronic origins of this behavior remain unresolved. Our systematic first-principles calculations of its point defects using the Heyd–Scuseria–Ernzerhof hybrid functional indicate that the major source of carrier electrons in undoped La2SnO2S3 is unintentionally incorporated H impurities rather than native defects. Moreover, the electrophilic behavior of La2SnO2S3 is unveiled as a pivotal limiting factor for its n-type doping, where carrier electrons are readily trapped around Sn sites in the presence of S vacancies and interstitial H impurities, and even without these defects through self-trapping. This carrier-trapping mechanism is as significant as the electron compensation by Sn vacancies as major acceptor-type native defects. Our synthesis and characterization of polycrystalline La2SnO2S3 confirm its moderate n-type conductivity and the presence of H impurities with a sizable concentration, both of which are in line with the theoretically predicted mechanism. These results clarify crucial limiting factors of n-type conductivity in La2SnO2S3 and provide a fundamental guideline for the design of related n-type oxychalcogenides.

Graphical abstract: Carrier generation and compensation mechanism in La2SnO2S3

Supplementary files

Article information

Article type
Paper
Submitted
20 Mar 2024
Accepted
29 Jun 2024
First published
10 Jul 2024

J. Mater. Chem. C, 2024,12, 12015-12025

Carrier generation and compensation mechanism in La2SnO2S3

T. Nagafuji, K. Osuna, K. Hanzawa, T. Gake, S. Bae, Z. Hu, T. Katase, A. Takahashi, H. Hiramatsu and F. Oba, J. Mater. Chem. C, 2024, 12, 12015 DOI: 10.1039/D4TC01116C

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