Atomically Thin Membrane Encapsulation for Cold Cathode Field Emitters

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Solution Overview

Problem

Field emitter arrays used in cold cathode devices suffer from reduced lifetime and performance in non-vacuum environments due to gas molecule adsorption and ion interaction, which limits their operational flexibility and reliability.

Innovation Solution

An atomically thin membrane, such as graphene or silicon nitride, is used to encapsulate the field electron emitter, creating an airtight seal that allows electron transmission while preventing gas molecules from reaching the emitter, enabling operation in various environments and enhancing device lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If field emitter arrays are operated in non-vacuum environments, then operational flexibility and ease of use are improved, but device lifetime and performance deteriorate due to gas molecule adsorption and ion interaction

Engineering Contradiction:

Improveoperational flexibilityVSAvoiddevice lifetime

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The device is segmented into two distinct environments: a vacuum chamber containing the field emitter array for optimal performance, and an external non-vacuum environment for operational flexibility. The electron-transparent membrane acts as the boundary between these segments, allowing the FEA to operate in vacuum while the overall device can be used in non-vacuum conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electron-transparent membrane serves as an intermediary barrier that selectively separates gas molecules from the field emitter array while permitting electron transmission. This intermediary component enables the FEA to maintain vacuum conditions internally while the device externally operates in non-vacuum environments, resolving the contradiction between operational flexibility and device lifetime.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If field emitter arrays are operated in vacuum environments, then device lifetime and performance are improved, but operational flexibility and ease of use deteriorate

Engineering Contradiction:

Improvedevice lifetimeVSAvoidoperational flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

An electron-transparent membrane (a thin film) is introduced as part of the vacuum chamber structure. This membrane allows the vacuum environment to be maintained in the FEA region while enabling the device to interface with non-vacuum environments externally, thus maintaining reliability while improving operational flexibility.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If an electron-transparent membrane is introduced to protect the field emitter, then device lifetime and environmental adaptability are improved, but device complexity increases

Engineering Contradiction:

Improvedevice lifetimeVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electron-transparent membrane serves as a thin film protective barrier that integrates into the vacuum chamber structure. While it does add a component, its thin-film nature minimizes the increase in overall device complexity compared to traditional robust vacuum chamber designs, while significantly improving reliability and environmental adaptability.

Inventive Principle:

Principle #30Flexible shells and thin films

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

The encapsulation with an electron-transparent membrane allows field emitter devices to maintain high current density and long lifetimes even in non-vacuum conditions, enabling modular design and wide-range environmental deployment.

Implementation Method 1

an atomically thin membrane positioned in the first direction with respect to the field electron emitter

Methodology Applied

Scientific EffectElectron transmission through thin membrane:

Implementation Method 2

the potential barrier can be deformed by the application of an electric field to a point where electrons can quantum tunnel through the barrier. This latter phenomenon is termed 'field emission.'

Methodology Applied

Scientific EffectField emission:

Data Source

PatentUS10832885B2Electron transparent membrane for cold cathode devices

Publication Date: 2020.11.10 MASSACHUSETTS INST OF TECH

AI summary

According to some aspects, a cold cathode device is provided, the device comprising a substrate, a field electron emitter disposed upon the substrate and configured to emit electrons in a first direction, and a structure encapsulating the field electron emitter, thereby creating an airtight seal around the field electron emitter, at least a portion of the structure being an atomically thin membrane positioned in the first direction with respect to the field electron emitter. According to some embodiments, at least one einzel lens may be located within the structure and configured to direct electrons emitted by the field electron emitter.