Tailoring Tungsten Oxide Layers for Cold Field Emission Cathodes: Anodization and Thermal Oxidation Approaches

Tailoring Tungsten Oxide Layers for Cold Field Emission Cathodes: Anodization and Thermal Oxidation Approaches

Článek WoS

This study explores the optimization of tungsten oxide layers formed via thermal oxidation and anodization for cold field emission applications. Surface modifications can enhance tungsten emitters by improving the emission stability and reducing ion-induced damage. Polycrystalline tungsten samples were treated using two oxidation methods: thermal oxidation (at 550-750 degrees C, 103-104 Pa) and anodization (in 0.33 mol/L H3PO4 at 5-35 V). Lower temperatures and pressures (550 degrees C, 103 Pa) produced smoother (R a similar to 23 nm) and uniform oxide layers (similar to 240 nm thick), improving the high-voltage stability (7.5-8.5 kV). Anodized layers, while less stable at high voltages, exhibited enhanced emission at lower operational voltages (similar to 5.5-7 kV). Field emission microscopy confirmed that thermally oxidized layers perform better under high electrostatic fields, whereas anodized layers offer a rapid response and lower threshold voltages. These findings demonstrate that both oxidation techniques are scalable and tunable for optimizing cold field emitters, with tailored properties suited to specific applications in electron microscopy and related technologies.

This study explores the optimization of tungsten oxide layers formed via thermal oxidation and anodization for cold field emission applications. Surface modifications can enhance tungsten emitters by improving the emission stability and reducing ion-induced damage. Polycrystalline tungsten samples were treated using two oxidation methods: thermal oxidation (at 550-750 degrees C, 103-104 Pa) and anodization (in 0.33 mol/L H3PO4 at 5-35 V). Lower temperatures and pressures (550 degrees C, 103 Pa) produced smoother (R a similar to 23 nm) and uniform oxide layers (similar to 240 nm thick), improving the high-voltage stability (7.5-8.5 kV). Anodized layers, while less stable at high voltages, exhibited enhanced emission at lower operational voltages (similar to 5.5-7 kV). Field emission microscopy confirmed that thermally oxidized layers perform better under high electrostatic fields, whereas anodized layers offer a rapid response and lower threshold voltages. These findings demonstrate that both oxidation techniques are scalable and tunable for optimizing cold field emitters, with tailored properties suited to specific applications in electron microscopy and related technologies.

thermal oxidation; anodization; tungsten oxidethin films; cold field emission; surface engineering; electron microscopy; oxide layer optimization; vacuum technology

thermal oxidation; anodization; tungsten oxidethin films; cold field emission; surface engineering; electron microscopy; oxide layer optimization; vacuum technology

KOŠELOVÁ, Z.; ALLAHAM, M.; BURDA, D.; POKORNÁ, Z.; SOBOLA, D.; KNÁPEK, A.; FOHLEROVÁ, Z.

2026

18.04.2025

ACS Applied Electronic Materials

6

3

Spojené státy americké

12

https://pubs.acs.org/doi/abs/10.1021/acsaelm.5c00241