Nanoporous GaN via Conductivity-Based Selective Etch

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Solution Overview

Problem

Current methods for processing GaN semiconductor materials lack a flexible and efficient wet etching procedure to produce nanoporous structures with tunable optical and mechanical properties, which are essential for advanced electronic and optical applications.

Innovation Solution

An electrochemical etching process is employed, where GaN is exposed to an electrolyte and energized through a power supply to increase porosity, allowing for controlled pore formation and creation of nanoporous GaN with adjustable properties, suitable for various applications including light emitting diodes and nanotechnology.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional wet etching procedures are used for GaN, then the process is simple and familiar, but the ability to produce nanoporous structures with tunable properties is lacking

Engineering Contradiction:
Improveability to produce nanoporous structures with tunable propertiesVSAvoidetching process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by systematically varying etching voltage, current density, electrolyte composition, and temperature to control the formation of nanoporous structures in GaN. By adjusting these parameters, the process achieves tunable porosity (5-50%), pore size (10-100 nm), and crystallinity, transforming a simple etching process into a versatile nanoporous structure fabrication method.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If electrochemical etching is used to generate nanoporous GaN, then tunable optical and mechanical properties are achieved, but the process complexity increases compared to conventional methods

Engineering Contradiction:
Improvecontrol over porosity and crystallinityVSAvoidprocessing procedure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical and chemical etching methods with an electrochemical etching process. This substitution enables precise control over porosity and crystallinity through electrical parameters (voltage, current) rather than relying on mechanical abrasion or uncontrolled chemical reactions, achieving superior manufacturing precision despite increased process complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electrochemical etching process incorporates feedback mechanisms where the etching rate, porosity development, and crystallinity are monitored and controlled by adjusting applied voltage and current density in real-time. This feedback control enables precise achievement of target porosity levels and maintains GaN crystallinity throughout the etching process.

Inventive Principle:
Principle #23Feedback

3Illumination intensity

If porosity is increased in GaN to enhance optical properties, then light extraction is improved, but structural integrity may be compromised

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidstructural integrity
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

The patent optimizes the balance between light extraction and structural integrity by controlling porosity within the 5-50% range and pore size between 10-100 nm. At these parameter levels, sufficient porosity is achieved to enhance light extraction efficiency while maintaining adequate structural integrity for device fabrication and operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes controlled porous structures in GaN to enhance optical properties. The nanoporous network provides light scattering and trapping effects that improve extraction efficiency, while the controlled porosity level ensures the material retains sufficient mechanical strength for practical applications.

Inventive Principle:
Principle #31Porous materials

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 method generates nanoporous GaN with high crystallinity and tunable optical and mechanical properties, enabling the production of devices with enhanced light extraction, reduced defect densities, and cost-effective substrate recycling, while maintaining compatibility with existing semiconductor manufacturing techniques.

Implementation Method 1

exposing GaN to an electrolyte, coupling the GaN to one terminal of a power supply and an electrode, immersed in the electrolyte, to another terminal of the power supply to thereby form a circuit; and energizing the circuit to increase the porosity of at least a portion of the GaN

Methodology Applied
Scientific EffectElectrochemical etching: Electrolysis

Data Source

PatentEP3923352A1Conductivity based selective etch for GAN devices and applications thereof
Publication Date: 2021.12.15 YALE UNIVERSITY
  • EP3923352A1 patent drawingFigure 1~2
  • EP3923352A1 patent drawingFigure 3a~4b
  • EP3923352A1 patent drawingFigure 5a~6b

AI summary

This invention relates to methods of generating NP gallium nitride (GaN) across large areas (> 1 cm2) with controlled pore diameters, pore density, and porosity. Also disclosed are methods of generating novel optoelectronic devices based on porous GaN. Additionally a layer transfer scheme to separate and create free-standing crystalline GaN thin layers is disclosed that enables a new device manufacturing paradigm involving substrate recycling. Other disclosed embodiments of this invention relate to fabrication of GaN based nanocrystals and the use of NP GaN electrodes for electrolysis, water splitting, or photosynthetic process applications.