LED Intermediate Layer Band Gap Engineering
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Solution Overview
Problem
The expansion of LED applications is hindered by crystal defects in semiconductor layers grown on hetero-substrates, leading to reduced brightness due to lattice mismatch, which affects the reliability and luminous efficacy of light-emitting devices.
Innovation Solution
A light-emitting device structure is implemented with a support member, a first semiconductor layer, intermediate layers with varying band gaps, and an active layer, where layers with the largest band gap contact those with the smallest band gap, forming a multi-layer structure to prevent crystal defects and enhance current diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor layer is grown on a hetero-substrate, then the device structure is formed, but crystal defects occur due to lattice mismatch reducing reliability and brightness
Solution Approach 1:
The patent introduces an intermediate layer between the semiconductor layer and hetero-substrate that acts as a mediator to gradually transition the lattice structure. This intermediate layer reduces the abrupt lattice mismatch, preventing crystal defects from forming while maintaining the device structure integrity.
Solution Approach 2:
The patent modifies the lattice parameters by using an intermediate layer with specific compositional gradients. By changing the material composition and lattice constants progressively through the intermediate layer, the patent eliminates the harmful lattice mismatch effect between the semiconductor layer and hetero-substrate.
2Productivity
If a single-layer structure is used, then the device is simpler to manufacture, but current diffusion is insufficient reducing luminous efficacy
Solution Approach 1:
The patent divides the intermediate layer into multiple sub-layers with different compositions and thicknesses. This segmentation allows each sub-layer to perform specific functions in the current diffusion process, improving overall luminous efficacy while managing the complexity through systematic design.
Solution Approach 2:
The patent uses composite material structures in the intermediate layer, combining different semiconductor materials with complementary properties. This composite approach enables effective current diffusion across the layer structure, enhancing luminous efficacy without requiring overly complex device architectures.
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 reduces crystal defects, improves the crystallinity of the active layer, and increases the luminous efficiency of the light-emitting device by effectively diffusing current and reducing stress between layers with different band gaps.
Implementation Method 1
improve brightness through effective diffusion of current
Implementation Method 2
reducing stress between layers with different band gaps
Implementation Method 3
A light-emitting diode (LED) is a device which converts electric signals into light using characteristics of compound semiconductors
Data Source
AI summary
Disclosed is a light-emitting device including: a support member; and a light-emitting structure on the support member, the light-emitting structure including a first semiconductor layer, at least one intermediate layer, an active layer and a second semiconductor layer, wherein the intermediate layer is on at least one of upper and lower regions of the active layer and comprises at least four layers, wherein the layers have different band gaps, and wherein, among the layers, a layer having the largest band gap contacts a layer having the smallest band gap. Based on this configuration, it is possible to reduce crystal defects and improve brightness of the light-emitting device through effective diffusion of current.