Single-Crystal HfC Emitter Tip Sharpening for Stable Electron Emission

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Solution Overview

Problem

Existing methods for sharpening emitter tips, such as electrochemical etching and focused ion beam milling, face challenges with surface contamination and stoichiometric composition changes, leading to impaired performance and complexity in controlling ion beam direction, while hafnium carbide nanowire emitters have instability in electron emission characteristics.

Innovation Solution

A method involving the use of a focused ion beam in a vacuum to sharpen the tip of single crystal materials like hafnium carbide without chemical treatment, ensuring the periphery is open to precisely control the tip's curvature and maintain stoichiometric composition, resulting in stable and efficient electron emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrochemical etching is used to sharpen the emitter tip, then the fabrication steps can be reduced, but surface contamination occurs and stoichiometric composition becomes disproportional

Engineering Contradiction:

Improvefabrication stepsVSAvoidsurface contamination and stoichiometric composition

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs focused ion beam processing in a vacuum environment, which is an inert atmosphere that prevents chemical reactions between the emitter material and ambient gases. This eliminates surface contamination and maintains stoichiometric composition while still achieving tip sharpening, resolving the contradiction between reduced fabrication steps and manufacturing precision.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Manufacturing precision

If focused ion beam milling is used to remove surface defects, then surface quality improves, but the device configuration becomes complicated for controlling ion beam direction

Engineering Contradiction:

Improvesurface qualityVSAvoiddevice configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of directing the ion beam along the longitudinal axis of the emitter as in conventional methods, this patent inverts the approach by directing the ion beam from the side (radial direction) toward the tip. This simplified configuration achieves the same surface quality improvement without requiring complex device arrangements for longitudinal beam control.

Inventive Principle:

Principle #13The other way round (Inversion)

3Shape

If conventional ion beam processing is used, then tip sharpening is achieved, but surface contamination occurs due to chemical treatment

Engineering Contradiction:

Improvetip sharpeningVSAvoidsurface contamination

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent performs all ion beam processing operations in a vacuum environment, preventing chemical reactions that would cause surface contamination. The focused ion beam sharpens the tip while the vacuum atmosphere protects the surface from contamination, simultaneously achieving both objectives.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

4Productivity

If hafnium carbide nanowire emitters are used, then electron emission is achieved, but stability of electron emission characteristics deteriorates

Engineering Contradiction:

Improveelectron emissionVSAvoidstability of electron emission characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces chemical treatment methods with purely physical ion beam processing in vacuum. This mechanical/physical substitution avoids chemical reactions that destabilize the emitter material, maintaining both electron emission capability and long-term stability of emission characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach simplifies the sharpening process, enhances electron emission stability and efficiency, and prevents surface contamination, leading to improved performance in electron guns and electronic devices.

Implementation Method 1

processing a single crystal material in a vacuum using a focused ion beam to form an end of the single crystal material, through which electrons are to be emitted, into a tapered shape

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 2

processing a single crystal material in a vacuum using a focused ion beam

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentUS11915920B2Emitter, electron gun in which same is used, electronic device in which same is used, and method for manufacturing same

Publication Date: 2024.02.27 NAT INST FOR MATERIALS SCI

AI summary

The present invention provides a simpler method for sharpening a tip of an emitter. In addition, the present invention provides an emitter including a nanoneedle made of a single crystal material, an emitter including a nanowire made of a single crystal material such as hafnium carbide (HfC), both of which stably emit electrons with high efficiency, and an electron gun and an electronic device using any one of these emitters. A method for manufacturing the emitter according to an embodiment of the present invention comprises processing a single crystal material in a vacuum using a focused ion beam to form an end of the single crystal material, through which electrons are to be emitted, into a tapered shape, wherein the processing is performed in an environment in which a periphery of the single crystal material fixed to a support is opened.