Composite Substrate for LED Light Extraction
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Solution Overview
Problem
Current photoelectronic elements, such as LEDs, face challenges in optimizing light-emitting efficiency and reliability due to limitations in substrate design and current distribution, leading to inefficient light absorption and emission.
Innovation Solution
A composite substrate with an insulative and conductive structure, including a bonding layer, current spreading layers, and a current blocking layer, is used to enhance current distribution and reduce light absorption, while a window layer and high band-gap regions are introduced to scatter light and alter current paths, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional substrate design is used for photoelectronic elements, then the structure is simple and easy to manufacture, but the light-emitting efficiency and current distribution are insufficient
Solution Approach 1:
The substrate is divided into multiple functional layers including insulative substrate, conductive substrate, bonding layer with conductive and insulative regions, current spreading layers, and current blocking layer. Each layer performs a specific function to optimize light emission and current distribution, resolving the contradiction between structural complexity and emission efficiency.
Solution Approach 2:
The substrate employs composite material structure combining electrically insulative materials (sapphire, glass, ceramic) and electrically conductive materials (metal layers, conductive paste). This composite approach enables simultaneous achievement of electrical isolation, current conduction, and mechanical support, improving light-emitting efficiency while managing structural complexity.
2Reliability
If current spreading layers are added to optimize current distribution, then the current flow is improved, but the device complexity increases
Solution Approach 1:
The bonding layer is designed with spatially varying properties, containing both conductive regions (for current injection) and insulative regions (for electrical isolation). The current spreading layers are positioned at specific locations where current distribution optimization is most needed, applying local quality improvements without unnecessary complexity throughout the entire device.
Solution Approach 2:
The bonding layer serves multiple functions simultaneously: it provides mechanical bonding between substrates, establishes electrical connections through conductive regions, and provides electrical isolation through insulative regions. This multi-functionality reduces the need for separate dedicated layers, managing complexity while improving current distribution.
3Productivity
If the substrate structure is optimized for light emission, then the light-emitting efficiency is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The substrate layers and their electrical/optical properties are pre-configured during substrate fabrication before the photoelectronic element assembly. The bonding layer's conductive and insulative regions are predetermined, and current spreading layers are pre-positioned, allowing for standardized manufacturing processes that reduce complexity despite the sophisticated final 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
This configuration improves light-emitting efficiency and reliability by optimizing current flow and light scattering, reducing light absorption and increasing the effectiveness of the photoelectronic element.
Implementation Method 1
a bonding layer including an electrically conductive region and an electrically insulative region
Implementation Method 2
a first current spreading layer; a second current spreading layer
Implementation Method 3
a window layer
Implementation Method 4
the first active layer of the photoelectronic element includes a high band-gap region
Data Source
AI summary
A photoelectronic element includes an electrically insulative substrate, an electrically conductive substrate, an intermediate layer and a semiconductor stacked layer. The electrically insulative substrate has a top surface. The electrically conductive substrate has a lower portion, and an upper portion surrounded by the electrically insulative substrate and coplanar with the top surface. The intermediate layer has a first portion formed directly under the electrically insulative substrate and above the electrically conductive substrate, a second portion and a bent portion formed between the first portion and the second portion. The semiconductor stacked layer has an light-emitting active layer with a high band gap, disposed on the electrically insulative substrate and the upper portion.