Coplanar-gate ZnO nanowire field emitter arrays with enhanced gate-control performance using a ring-shaped cathode

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Nanowire field emitters show promise for large-area gated field emitter arrays (FEAs).
• Field-screening effects in conventional FEAs limit gate voltage regulation and emission currents.
• Micrometer-scale cathode patterns hinder the performance of existing FEA devices.

Purpose of the Study:

• To propose and investigate a ring-shaped ZnO nanowire pad structure to enhance FEA performance.
• To overcome limitations imposed by field-screening effects in nanowire-based FEAs.
• To improve gate-controlled characteristics and electron emission efficiency in large-area FEAs.

Main Methods:

• Fabrication of ring-shaped ZnO nanowire pad arrays.
• Diode measurements to characterize field emission properties (turn-on field, current density).
• Integration of ZnO nanowire pad arrays into coplanar-gate FEAs.
• Microscopic in-situ measurements to study gate-controlled field emission.
• Simulations and experimental analysis to understand enhanced device capabilities.

Main Results:

• Ring-shaped ZnO nanowire pad arrays exhibited uniform emission.
• Achieved a turn-on field of 5.9 V/µm and current density of 4.6 mA/cm² at 9 V/µm.
• Enhanced gate-controlled device characteristics were obtained after integration into coplanar-gate FEAs.
• Increased edge area due to the ring shape led to more efficient electron emission.

Conclusions:

• The ring-shaped ZnO nanowire pad design effectively mitigates field-screening effects.
• This structure significantly enhances gate-controlled capabilities in FEAs.
• The findings are crucial for developing advanced large-area gate-controlled FEAs using nanowire emitters for vacuum electronics.