Inverted LED Structure with Tunnel Diode for High Light Output
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) with a p-region above the active zone have low light output, and achieving higher light output requires complex and costly additional bonding processes, while LEDs with a p-region below the active layer suffer from absorption losses and require high-power configurations.
Innovation Solution
A light-emitting diode with a stacked structure featuring a carrier layer, mirror layer, n-doped lower cladding layer, active electromagnetic radiation-generating layer, p-doped upper cladding layer, and an n-doped current distribution layer, where a tunnel diode is placed above the active layer to enhance light output and conductivity, using Ga-containing layers and a filling material with metallic conductivity to reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a p-region is placed above the active zone to maintain conventional polarity, then the structure maintains standard polarity configuration, but the light output is very low
Solution Approach 1:
The patent inverts the conventional LED structure by placing the p-region below the active layer instead of above it. This polarity reversal allows the light-emitting surface to be on the side with the n-contact, eliminating the need for complex bonding processes while significantly increasing light output. The tunnel diode structure enables this inversion by providing the necessary electrical functionality in the reversed configuration.
Solution Approach 2:
The patent introduces a tunnel diode as an intermediary structure between the active layer and the n-contact. This tunnel diode enables the inverted polarity configuration to function properly by providing the necessary electrical characteristics that allow high light output while maintaining the reversed structural arrangement.
2Illumination intensity
If a mirror layer is integrated to increase light output, then light efficiency is improved, but the structure requires p-region below the active layer which increases complexity
Solution Approach 1:
The patent merges the mirror layer functionality with the existing structure by integrating it into the inverted configuration. The mirror layer is positioned to work in conjunction with the inverted p-region and tunnel diode structure, achieving high light output without requiring separate complex bonding processes or auxiliary carrier materials.
3Reliability
If n-doped current distribution layer is used with polarity reversal, then transverse conductivity is higher and absorption losses are lower, but the layer sequence becomes non-conventional
Solution Approach 1:
The patent applies polarity reversal to the layer sequence, placing the n-doped current distribution layer in a non-conventional position. This inversion results in higher transverse conductivity and lower absorption losses, as the n-type doping provides better electrical characteristics for current distribution in the inverted structure.
Solution Approach 2:
The patent changes the doping parameters and layer sequence to optimize performance. By using n-doped layers with specific doping concentrations and positioning them in the inverted structure, the patent achieves superior electrical and optical performance compared to conventional p-doped configurations.
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 increases light output simply and cost-effectively while maintaining the polarity of the structure, achieving comparable or better performance than prior art with lower absorption losses and higher transverse conductivity, and allows for easy replacement of high-power LEDs without redesign.
Implementation Method 1
A tunnel diode is arranged between the upper cladding layer and the current distribution layer
Implementation Method 2
an active electromagnetic radiation-generating layer
Implementation Method 3
a mirror layer
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Light-emitting diode with a stacked structure, wherein the stacked structure comprises a substrate layer, a mirror layer, an n-doped lower cladding layer, an active electromagnetic radiation-generating layer, a p-doped upper cladding layer, and an n-doped current-distributing layer, the aforementioned layers being arranged in the stated order. The active layer comprises a quantum well structure. A tunnel diode is arranged between the upper cladding layer and the current-distributing layer, the current-distributing layer consisting predominantly of an n-doped Ga-containing layer with a Ga content > 1%.