Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection
Notwithstanding the success of SnO<sub>2</sub> as a fundamental material for gas sensing, it has often been criticized for its cross-sensitivity and high operational temperatures. Therefore, in this study, RF-sputtered SnO<sub>2</sub> thin films were subjected to a modificati...
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2025-04-01
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| author | Marwen Mezyen Nabila Bitri Ibtissem Riahi Fatma Chaabouni Eduard Llobet |
| author_facet | Marwen Mezyen Nabila Bitri Ibtissem Riahi Fatma Chaabouni Eduard Llobet |
| author_sort | Marwen Mezyen |
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| description | Notwithstanding the success of SnO<sub>2</sub> as a fundamental material for gas sensing, it has often been criticized for its cross-sensitivity and high operational temperatures. Therefore, in this study, RF-sputtered SnO<sub>2</sub> thin films were subjected to a modification process through doping with a rare earth element, dysprosium (Dy), and subsequently deposited onto two different types of substrates: alumina and glass substrates. All thin films underwent a comprehensive series of characterizations aimed at ensuring their suitability as NO<sub>2</sub> sensors. The dysprosium doping levels ranged from 1 to 7 wt.% in increments of 2% (wt.%). X-ray patterns showed that all deposited films exhibited the tetragonal rutile structure of SnO<sub>2</sub>. The optical band gap energy (Eg) increased with Dy doping, while the Urbach energy decreased with Dy doping. Field emission scanning electron microscopy (FESEM) revealed highly compacted grainy surfaces with high roughness for alumina substrate thin films, which also exhibited higher resistivity that increased with the levels of Dy doping. Energy-dispersive X-ray spectroscopy (EDX) analyses confirmed the stoichiometry of both types of thin films. Gas sensing tests were conducted at different operating temperatures, where the highest response to nitrogen dioxide, over 42%, was recorded for the higher dopant level at 250 °C. Moreover, the sensor’s selectivity toward nitrogen dioxide traces was evaluated by introducing interfering gases at higher concentrations. However, the sensors showed also significant responses when operated at room temperature. Also, we have demonstrated that higher stability is related to the temperature of the sensors and Dy ratio. Hence, a detailed discussion of the gas-sensing mechanisms was undertaken to gain a deeper insight into the NO<sub>2</sub> sensitivity exhibited by the Dy-doped SnO<sub>2</sub> layer. |
| format | Article |
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| issn | 2227-9040 |
| language | English |
| publishDate | 2025-04-01 |
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| series | Chemosensors |
| spelling | doaj-art-213ef236783c4a8b80862bfdb712785c2025-08-20T03:14:15ZengMDPI AGChemosensors2227-90402025-04-0113412110.3390/chemosensors13040121Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas DetectionMarwen Mezyen0Nabila Bitri1Ibtissem Riahi2Fatma Chaabouni3Eduard Llobet4Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire El-Manar, El Manar Tunis 2092, TunisiaLaboratoire de Photovoltaïque et Matériaux Semi-Conducteurs, Ecole Nationale d’Ingénieurs de Tunis, Université de Tunis El Manar, Tunis 1002, TunisiaFaculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire El-Manar, El Manar Tunis 2092, TunisiaLaboratoire de Photovoltaïque et Matériaux Semi-Conducteurs, Ecole Nationale d’Ingénieurs de Tunis, Université de Tunis El Manar, Tunis 1002, TunisiaSchool of Engineering, MINOS, Universitat Rovira i Virgili, Avda. Països Catalans 26, 43007 Tarragona, SpainNotwithstanding the success of SnO<sub>2</sub> as a fundamental material for gas sensing, it has often been criticized for its cross-sensitivity and high operational temperatures. Therefore, in this study, RF-sputtered SnO<sub>2</sub> thin films were subjected to a modification process through doping with a rare earth element, dysprosium (Dy), and subsequently deposited onto two different types of substrates: alumina and glass substrates. All thin films underwent a comprehensive series of characterizations aimed at ensuring their suitability as NO<sub>2</sub> sensors. The dysprosium doping levels ranged from 1 to 7 wt.% in increments of 2% (wt.%). X-ray patterns showed that all deposited films exhibited the tetragonal rutile structure of SnO<sub>2</sub>. The optical band gap energy (Eg) increased with Dy doping, while the Urbach energy decreased with Dy doping. Field emission scanning electron microscopy (FESEM) revealed highly compacted grainy surfaces with high roughness for alumina substrate thin films, which also exhibited higher resistivity that increased with the levels of Dy doping. Energy-dispersive X-ray spectroscopy (EDX) analyses confirmed the stoichiometry of both types of thin films. Gas sensing tests were conducted at different operating temperatures, where the highest response to nitrogen dioxide, over 42%, was recorded for the higher dopant level at 250 °C. Moreover, the sensor’s selectivity toward nitrogen dioxide traces was evaluated by introducing interfering gases at higher concentrations. However, the sensors showed also significant responses when operated at room temperature. Also, we have demonstrated that higher stability is related to the temperature of the sensors and Dy ratio. Hence, a detailed discussion of the gas-sensing mechanisms was undertaken to gain a deeper insight into the NO<sub>2</sub> sensitivity exhibited by the Dy-doped SnO<sub>2</sub> layer.https://www.mdpi.com/2227-9040/13/4/121SnO<sub>2</sub>Dysputteringoptical and morphological propertiesNO<sub>2</sub>gas sensing |
| spellingShingle | Marwen Mezyen Nabila Bitri Ibtissem Riahi Fatma Chaabouni Eduard Llobet Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection Chemosensors SnO<sub>2</sub> Dy sputtering optical and morphological properties NO<sub>2</sub> gas sensing |
| title | Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection |
| title_full | Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection |
| title_fullStr | Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection |
| title_full_unstemmed | Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection |
| title_short | Optimizing Sputtered SnO<sub>2</sub>:Dy Thin Films for NO<sub>2</sub> Gas Detection |
| title_sort | optimizing sputtered sno sub 2 sub dy thin films for no sub 2 sub gas detection |
| topic | SnO<sub>2</sub> Dy sputtering optical and morphological properties NO<sub>2</sub> gas sensing |
| url | https://www.mdpi.com/2227-9040/13/4/121 |
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