Electrospun Indium-doped Nanofibers Based on Gallium Oxide: Fabrication and Characterization

Gallium oxide-based nanofibers (NFs) have gained increasing attention due to their unique combination of physical, optical, and chemical properties. These features make Ga₂O₃ NFs promising materials for UV photodetectors, gas sensors, and optoelectronic devices. However, the effects of dopants on the properties of Ga₂O₃ NFs remain insufficiently studied. This work focuses on the synthesis of undoped and indium-doped Ga₂O₃ nanofibers by electrospinning and the investigation of their structural, morphological, and optical properties.

Polyvinylpyrrolidone was used as a polymer matrix. Gallium nitrate Ga(NO₃)₃·8H₂O (99.9%) and indium nitrate In(NO₃)₃·4½H₂O (99.99%) served as metal precursors. The Ga precursor concentration was 2 wt.%, while indium was introduced at 5 and 10 wt.% relative to gallium. A 1:1 mixture of distilled water and ethanol was used as a solvent.

Electrospinning was carried out under 25 kV, with a feed rate of 1.8 mL/h, at 25 ± 1 °C and 30 ± 1% RH for 40 minutes. The as-spun fibers were dried for 15 minutes in a chamber and then for 48 hours at room temperature. Thermal annealing was performed at 900 °C for 4 hours (heating rate: 5 °C/min) with natural cooling.

Morphological analysis was conducted using SEM and EDS. The optical bandgap was determined by the Tauc-plot method. Indium doping at 10 wt.% led to a 0.35 eV reduction in bandgap, in good agreement with theoretical predictions.

This research was funded by the Ministry of Science and Higher Education of the Russian Federation (project No. FSER-2025-0005).