Microcavity Plasma Devices with Non-Uniform Cross-Section
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Solution Overview
Problem
Existing microcavity plasma devices lack control over non-uniform cross-sectional geometry of microcavities, limiting their operational efficiency and photon extraction capabilities compared to semiconductor-fabricated devices.
Innovation Solution
A method involving pre-anodization and photoresist patterning to form microcavities with controllable, non-uniform sidewall profiles, allowing for precise shaping of microcavities and integration of buried electrodes within metal/metal oxide structures, enabling optimized emission and operating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor fabrication techniques are used to create microcavities, then control over cross-sectional geometry is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent changes the fabrication approach from semiconductor techniques to anodization of metal foils, allowing control over microcavity geometry through electrochemical parameter adjustment (voltage, time, electrolyte composition) rather than complex photolithography and etching processes
Solution Approach 2:
The patent uses inexpensive metal foils (aluminum, stainless steel) as the substrate for microcavity formation, replacing expensive semiconductor wafers. The foils can be easily discarded or replaced, simplifying the manufacturing process while maintaining geometric control
2Ease of manufacture
If uniform cross-section microcavities are used, then manufacturing is simpler, but photon extraction efficiency decreases
Solution Approach 1:
The patent introduces asymmetric, non-uniform cross-sectional geometries in microcavities formed through anodization, where the cavity walls have varying thickness and curvature. This asymmetry enhances light extraction by reducing total internal reflection at the cavity boundaries, improving photon efficiency while maintaining relatively simple fabrication
Solution Approach 2:
The patent creates local variations in microcavity geometry (different wall angles, curvatures, and thicknesses at different locations) to optimize specific functions such as light extraction at critical interfaces, while the overall fabrication process remains uniform and simple
3Use of energy by moving object
If tapered microcavities are fabricated in silicon, then light extraction is improved, but the sidewall angle is fixed by crystalline structure
Solution Approach 1:
The patent enables continuous variation of microcavity geometry parameters (sidewall angle, curvature, cross-sectional shape) by changing anodization parameters (voltage, time, electrolyte composition, temperature), providing adaptability that fixed crystalline structures cannot offer
Solution Approach 2:
The patent replaces the mechanical constraint of fixed crystalline sidewall angles with electrochemical control through anodization, allowing the microcavity geometry to be defined by process parameters rather than material structure
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 solution allows for tailored and optimized microcavity plasma device arrays with improved power efficiency, linearity of voltage-current characteristics, and enhanced photon extraction, reducing power consumption and simplifying control circuitry while maintaining the advantages of inexpensive, flexible metal/metal oxide structures.
Implementation Method 1
a first electrode pre-formed with microcavities having the desired cross-sectional geometry. Pre-formed screen-like metal foil, e.g. Al screens used in the battery industry, can be used with the disclosed methods. Oxide is subsequently grown on the foil, including on the inside walls of the microcavities (where plasma is to be produced), by wet electrochemical processing (anodization) of the foil.
Implementation Method 2
Microcavity plasma devices produce a nonequilibrium, low temperature plasma within, and essentially confined to, a cavity having a characteristic dimension d below approximately 500 μm
Data Source
AI summary
An embodiment of the invention IS an array of microcavity plasma devices The array includes a first metal film electrode with a plurality of non-uniform cross-section microcavities therein that are encapsulated in oxide A second electrode is a thin metal foil encapsulated in oxide that is bonded to the first electrode A packaging layer contains gas or vapor in the non-uniform cross-section microcavities To make such device, photoresist is patterned to encapsulate the anodized foil or film except on a top surface at desired positions of microcavities A second anodization or electrochemical etching is conducted to form the non-uniform cross-section sidewall microcavities cavities After removing photoresist and metal oxide, a final anodization lines the walls of the microcavities with metal oxide and fully encapsulates the metal electrodes with metal oxide.