Quantum Well LED Structure for Uniform Carrier Distribution
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in achieving high luminous intensity, efficiency, and anti-aging performance, particularly under high current density conditions, leading to issues with charge carrier distribution and heat management.
Innovation Solution
A light-emitting device with a semiconductor epitaxial structure featuring a quantum well structure with varying well and barrier layer thicknesses and aluminum content, where the bandgap of the barrier layer decreases and the well layer thickness increases from the first surface to the second surface, enhancing charge carrier distribution and reducing overflow, thereby improving luminous intensity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional quantum well structure with uniform well layer thickness is used, then the device structure is simple, but the charge carrier distribution is uneven and electron overflow occurs under high current densities
Solution Approach 1:
The patent applies local quality by varying the well layer thickness and barrier layer bandgap across different regions of the quantum well structure. Specifically, the well layer thickness decreases from the first surface to the second surface, and the barrier layer bandgap increases from the first surface to the second surface. This spatial variation in structural parameters creates localized differences in charge carrier confinement and transport properties, ensuring even charge carrier distribution throughout the active layer and preventing electron overflow at any single location.
2Illumination intensity
If the well layer thickness is increased to improve light emission, then the luminous intensity increases, but the charge carrier distribution becomes more uneven
Solution Approach 1:
The patent implements local quality by creating a gradient in well layer thickness where the thickness varies spatially from the first surface to the second surface. This gradient structure ensures that regions with higher charge carrier concentration have thinner well layers that provide stronger confinement, while regions with lower concentration have thicker well layers that allow better carrier supply. The barrier layer bandgap is simultaneously varied to complement this thickness variation, creating localized zones with optimized carrier confinement and transport properties that collectively achieve uniform distribution across the entire active layer.
Solution Approach 2:
The patent applies parameter changes by systematically varying the well layer thickness and barrier layer bandgap as continuous parameters across the quantum well structure. The well layer thickness is reduced from the first surface toward the second surface, while the barrier layer bandgap is increased in the same direction. These parameter variations are designed to compensate for the non-uniform charge carrier distribution that would otherwise occur in a uniform structure, ensuring that the product of well layer thickness and carrier concentration remains relatively constant throughout the active layer, thereby maintaining uniform charge carrier distribution while preserving high luminous intensity.
3Productivity
If high current density is applied to increase luminous flux, then the luminous efficiency improves, but electron overflow and heat-related issues worsen
Solution Approach 1:
The patent applies local quality by creating spatially varying well layer thickness and barrier layer bandgap across the quantum well structure. The well layer thickness decreases from the first surface to the second surface, while the barrier layer bandgap increases in the same direction. This localized variation in structural parameters creates regions with different carrier confinement and transport characteristics, ensuring that charge carriers are evenly distributed throughout the active layer even under high current density operation. This prevents electron overflow at any single location and reduces localized heat generation, thereby enabling high luminous flux output without the harmful effects of electron overflow and heat-related degradation.
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 enhances light-emitting efficiency, luminous intensity, and anti-aging performance by ensuring even charge carrier distribution and reducing heat-related issues, resulting in lower light attenuation and higher luminous flux compared to conventional LEDs.
Implementation Method 1
The active layer includes a quantum well structure having multiple periodic units, each of which includes a well layer and a barrier layer disposed sequentially in such order, and a bandgap of the barrier layer is greater than that of the well layer
Implementation Method 2
Light-emitting diodes (LEDs) are considered to be one of the light sources having the most potential as they offer advantages including high luminous intensity, high efficiency
Data Source
AI summary
A light-emitting device includes a semiconductor epitaxial structure that has a first surface and a second surface, and that includes a first semiconductor layer, an active layer, and a second semiconductor layer. The active layer includes a quantum well structure having multiple periodic units, each including a well layer and a barrier layer greater in bandgap than the well layer. The bandgap of the barrier layer of at least one of the periodic units proximate to the first surface is smaller than that proximate to the second surface, and a thickness of the well layer of at least one of the periodic units proximate to the first surface is greater than that proximate to the second surface. In some embodiments, a bandgap of a second spacing layer disposed between the active and second semiconductor layers increases in a direction from the first surface to the second surface.