Polymer nanofiber-templated fabrication and characterization of gallium oxide nanofibers consisting of granular nanoparticles

Gallium oxide (β-Ga₂O₃) is an interesting semiconductor that has a wide bandgap and can be used as an optoelectronic material in flat-panel displays, solar energy conversion devices and optical limiters for UV light. However, it is difficult to fabricate and process Ga₂O₃ nanofibers for actual optoelectronic applications. When the excellent processability of polymeric materials is introduced into the inorganic nanofiber fabrication process, this limitation can be easily overcome. The aim of the research reported was to prepare granular Ga₂O₃ nanofibers utilizing an electrospun polyacrylonitrile nanofiber template combined with sol-gel technology. Ga₂O₃ nanofibers were successfully fabricated by electrospinning a solution of polyacrylonitrile mixed with gallium nitrate and subsequent calcination. The surface and bulk morphologies of the calcined nanofibers investigated using field-emission scanning electron microscopy and transmission electron microscopy (TEM) indicated that Ga₂O₃ nanofibers were constructed by the fusion of gallium oxide nanoparticles. TEM bright-field images combined with selected-area electron diffraction indicated that the average diameter of the Ga₂O₃ nanofibers produced was ca 55 nm and the crystalline structure was β-Ga₂O₃ with a monoclinic unit cell. Furthermore, the photoluminescence spectrum of the Ga₂O₃ nanofibers exhibited two strong green emission peaks and one UV emission peak. Gallium oxide (Ga₂O₃) nanofibers made up of continuously connected granular nanoparticles exhibiting one UV and two strong green emissions were fabricated using an electrospun polymer nanofiber template.