Discovery of Energy-Localized Trap States via Opto-Electrical Spectroscopy in UWBG Perovskite La:SrSnO3 FETs

초록

Strontium stannate perovskite (SrSnO3) is emerging as a promising material for next-generation ultra-wide bandgap (UWBG) semiconductors due to its high electron mobility and optical transparency. However, despite the critical importance of defect analysis to utilize La-doped SrSnO3 as a semiconductor channel material, the energy distribution of sub-gap states has not yet been sufficiently elucidated under bias conditions. In this work, we fabricated La-doped SrSnO3 top-gate metal-oxide-semiconductor field-effect transistors (MOSFETs) and characterized them under multi-wavelength light ranging from 300–900 nm, quantitatively extracting the trap density over a wide range of energy spectra. The transient decrease in transmittance observed at 400 nm correlates with subthreshold swing degradation, revealing deep donor-like traps as the dominant trap states. Notably, despite the presence of traps, La-doped SrSnO3 exhibits excellent optical durability with minimal threshold voltage fluctuations under multi-wavelength illumination. The resulting fabricated MOSFETs achieved a high on/off current ratio (∼1011), showing competitive performance and stability compared to previously reported oxide semiconductors. This work establishes an analytical framework for precisely unveiling the trap-dominated behavior of SrSnO3 and proposes essential design guidelines for the development of high-reliability power and optoelectronic devices based on next-generation UWBG perovskite semiconductors. © 2026 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH.

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