Ga₂O₃(Sn) Oxides for High-Temperature Gas Sensors

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Gallium(III) oxide (Ga₂O₃) is a wide-gap semiconductor suitable for high-temperature resistive gas sensors.
• Doping Ga₂O₃ with tin (Sn) can modify its electrical and sensing properties.

Purpose of the Study:

• To investigate the effect of tin doping on the structural, surface, and gas sensing properties of Ga₂O₃.
• To understand the relationship between tin content and sensor performance for CO and NH₃ detection.

Main Methods:

• Synthesis of Ga₂O₃(Sn) samples with varying tin content (0-13 at.%) via aqueous co-precipitation.
• Characterization using X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, and infrared spectroscopy.
• Gas sensing measurements using probe molecule techniques for CO and NH₃.

Main Results:

• Tin doping decreased crystallite size and increased the formation temperature of β-Ga₂O₃.
• Sensor responses to CO and NH₃ exhibited non-monotonous behavior with increasing tin content.
• Key factors influencing sensor response include donor center formation, changes in electron concentration, reactive oxygen species, metastable phases, and SnO₂ segregation.

Conclusions:

• Tin doping significantly impacts the physical and chemical properties of Ga₂O₃.
• The non-monotonous sensor response is attributed to a complex interplay of doping-induced effects.
• Optimizing tin content is crucial for developing effective Ga₂O₃-based gas sensors.