Porous III-Nitride Buffer for Strain Relief in Light Emitting Devices
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Solution Overview
Problem
Conventional III-nitride light emitting devices face strain issues due to lattice mismatch, leading to reduced thickness and efficiency of light emitting layers, especially when grown on sapphire or SiC substrates, which limits high-current and high-power operation.
Innovation Solution
Incorporating a porous III-nitride region between the substrate and the light emitting layer, allowing for a relaxed III-nitride layer with a larger in-plane lattice constant, which reduces strain and enables thicker, higher InN composition light emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If III-nitride light emitting layers are grown on sapphire or SiC substrates, then the device structure is stable and manufacturable, but lattice mismatch causes strain that limits layer thickness and reduces efficiency
Solution Approach 1:
A porous III-nitride buffer layer is introduced as an intermediary between the sapphire/SiC substrate and the light emitting layers. This buffer layer has a larger in-plane lattice constant that better matches the light emitting layer, reducing strain while maintaining structural stability. The porous structure allows for lattice relaxation without compromising the overall device architecture.
Solution Approach 2:
The in-plane lattice constant of the buffer layer is changed by creating a porous structure. This parameter change allows the buffer layer to accommodate the lattice mismatch between the substrate and light emitting layers, enabling thicker layers to be grown with reduced strain and improved efficiency.
2Productivity
If the light emitting layer thickness is increased to improve efficiency, then more material is available for light emission, but strain from lattice mismatch increases and causes defects
Solution Approach 1:
The porous III-nitride buffer layer serves as a mediator that reduces the strain transmitted from the substrate to the light emitting layers. This allows the light emitting layers to be grown thicker without accumulating excessive strain that would cause defects and compromise structural integrity.
3Ease of manufacture
If conventional epitaxial growth is used on sapphire substrates, then manufacturing is straightforward, but the in-plane lattice constant is limited by substrate mismatch
Solution Approach 1:
The in-plane lattice constant is changed by introducing a porous III-nitride buffer layer with a larger lattice constant. This allows the light emitting layers to achieve a larger in-plane lattice constant than would be possible with direct growth on sapphire substrates, improving the match with the light emitting material.
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 porous region reduces strain in the light emitting layers, enhancing the internal quantum efficiency and allowing for thicker, higher InN composition layers, thus improving the performance and operational capabilities of III-nitride light emitting devices.
Implementation Method 1
the III-nitride layer comprising InN may be at least partially relaxed, i.e. the III-nitride layer comprising InN may have an in-plane lattice constant larger than an in-plane lattice constant of a conventional GaN layer grown on sapphire
Data Source
AI summary
A device comprising a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region is disclosed. The device comprises a porous region. The device comprises a first layer disposed between the light emitting layer and the porous region. The device comprises a mask layer disposed between the porous region and the first layer. The device comprises a plurality of openings formed in the mask layer.