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<p>This study presents a comprehensive investigation into the fabrication, structural characterization, and gas-sensing performance of stoichiometric (SnTe) and tellurium-rich (Sn₂₀Te₈₀) chalcogenide thin films for the selective detection of nitrogen oxides (NO, NO₂) and hydrogen sulfide (H₂S) at ambient temperature. Thin films were synthesized via high-vacuum thermal evaporation onto interdigitated electrode (IDE) substrate, with phase-pure alloy formation confirmed through XRD, SEM and EDAX spectroscopy. SnTe exhibited a uniform microcrystalline morphology, while Sn₂₀Te₈₀ displayed dual-phase features comprising cubic SnTe and hexagonal Te, offering a high density of defect states and interfacial grain boundaries. Electrical response measurements reveal that the Te-enriched Sn₂₀Te₈₀ films demonstrate superior chemiresistive sensitivity (up to 150% for H₂S, 110% for NO, and 90% for NO₂ at ~ 5&#xa0;ppm), rapid response/recovery times (28–59&#xa0;s and 67–164&#xa0;s), and excellent selectivity over interfering gases. The enhanced performance is attributed to increased Te surface states facilitating electron–hole modulation and reversible adsorption–desorption kinetics. The interaction of NOₓ and H₂S with the p-type Sn–Te matrix alters carrier concentration via charge-transfer mechanisms: oxidizing NO₂ increases hole density, while reducing H₂S decreases it through electron donation, modulating the film's resistance. The results underscore the critical role of stoichiometric tailoring and microstructural engineering in optimizing gas–solid interface reactions, establishing Sn₂₀Te₈₀ as a promising candidate for next-generation, low-power, room-temperature gas sensors suitable for environmental and industrial applications.</p>

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Microstructure-dependent chemiresistive response of SnTe and Sn20Te80 thin films for NOₓ and H2S sensing

  • 期刊论文

  • 发表日期：

    2026年2月21日

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  • M. L. Tejaswini,
  • K. P. Lakshmi,
  • R. Kalpana,
  • Narayana Ashwath

摘要

This study presents a comprehensive investigation into the fabrication, structural characterization, and gas-sensing performance of stoichiometric (SnTe) and tellurium-rich (Sn₂₀Te₈₀) chalcogenide thin films for the selective detection of nitrogen oxides (NO, NO₂) and hydrogen sulfide (H₂S) at ambient temperature. Thin films were synthesized via high-vacuum thermal evaporation onto interdigitated electrode (IDE) substrate, with phase-pure alloy formation confirmed through XRD, SEM and EDAX spectroscopy. SnTe exhibited a uniform microcrystalline morphology, while Sn₂₀Te₈₀ displayed dual-phase features comprising cubic SnTe and hexagonal Te, offering a high density of defect states and interfacial grain boundaries. Electrical response measurements reveal that the Te-enriched Sn₂₀Te₈₀ films demonstrate superior chemiresistive sensitivity (up to 150% for H₂S, 110% for NO, and 90% for NO₂ at ~ 5 ppm), rapid response/recovery times (28–59 s and 67–164 s), and excellent selectivity over interfering gases. The enhanced performance is attributed to increased Te surface states facilitating electron–hole modulation and reversible adsorption–desorption kinetics. The interaction of NOₓ and H₂S with the p-type Sn–Te matrix alters carrier concentration via charge-transfer mechanisms: oxidizing NO₂ increases hole density, while reducing H₂S decreases it through electron donation, modulating the film's resistance. The results underscore the critical role of stoichiometric tailoring and microstructural engineering in optimizing gas–solid interface reactions, establishing Sn₂₀Te₈₀ as a promising candidate for next-generation, low-power, room-temperature gas sensors suitable for environmental and industrial applications.