Synthesis of Ultrawide Band Gap TeO2 Nanoparticles by Pulsed Laser Ablation in Liquids: Top Ablation versus Bottom Ablation

Ultrawide band gap (UWBG) semiconductors are the future components of electronic devices due to their large energy band gap (>3.2 eV). In this article, spherical TeO2 nanoparticles, with sizes around ∼39 ± 12 and ∼29 ± 6 nm, were successfully synthesized by irradiating a pure tellurium target, totally submerged in ethanol, using a "Top-ablation" or "Bottom-ablation" synthesis protocol, respectively. Mostly, α-TeO2 nanoparticles were created (>95%) with only a small amount of γ-TeO2 nanoparticles being produced (<5%). Both colloids exhibited a ζ-potential larger than |30 mV|, indicating a stable colloidal solution. The energy band gaps of the TeO2 nanoparticles synthesized by the Top-ablation and Bottom-ablation synthesis protocols were determined to be around 5.3 and 5.8 eV, respectively. Finally, TeO2 UWBG nanoparticles were successfully synthesized using either a Top-ablation or Bottom-ablation synthesis protocol. The main advantage of the Bottom-ablation synthesis protocol is its ability to obtain smaller nanoparticles compared to that of the Top-ablation synthesis protocol.