LED Stack Thinned Part for Photon Extraction
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Solution Overview
Problem
Current light-emitting diodes (LEDs) face inefficiencies in photon extraction, as only photons emitted within a specific solid angle are considered during efficiency measurements, leading to suboptimal performance, particularly from a single side of the LED.
Innovation Solution
A novel LED structure featuring a stack with a thinned part and specific electrode placement, where the first electrode contacts only the thinned part and the second electrode is separate, optimizing photon extraction by controlling the thickness and conductivity of semiconductor layers to enhance constructive interference and current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If texturing is formed on the emission surface to improve photon extraction, then light extraction efficiency is improved, but the quantity of photons reaching the emission surface remains limited
Solution Approach 1:
The patent segments the electrode contact area by creating a recess in the semiconductor layer, dividing the contact interface into distinct regions. This segmentation allows the first electrode to contact only the thinned part while the second electrode contacts the thicker region, enabling differentiated optical and electrical functions in different zones of the same device structure.
Solution Approach 2:
The patent applies local quality by creating a thinned part of the semiconductor layer at the first electrode contact region while maintaining the original thickness at the second electrode contact region. This local modification of layer thickness optimizes photon extraction at the emission surface while preserving appropriate current distribution through the bulk material.
2Reliability
If the first electrode contacts the entire first face to ensure good current distribution, then electrical conductivity is improved, but photon extraction efficiency from a single side decreases
Solution Approach 1:
The recess structure segments the first electrode contact area, allowing the first electrode to be positioned only over the thinned part. This segmentation enables the first electrode to have a smaller contact area while the second electrode contacts the remaining region, achieving both good current distribution through the bulk material and optimized photon extraction from the thinned region.
Solution Approach 2:
The patent introduces a vertical dimension variation by creating a recess (thickness variation) in the semiconductor layer. This dimensional change allows the electrodes to be positioned at different vertical levels, with the first electrode contacting the thinned region and the second electrode contacting the thicker region, thereby optimizing both current distribution and photon extraction without requiring the first electrode to cover the entire surface.
3Loss of energy
If the stack thickness is reduced to improve photon extraction, then light extraction efficiency is improved, but current distribution becomes inappropriate
Solution Approach 1:
The patent applies local quality by creating a thinned part only at the region contacted by the first electrode, while maintaining the original stack thickness at the region contacted by the second electrode. This localized thickness reduction improves photon extraction efficiency from the emission surface while preserving sufficient material thickness to ensure appropriate current distribution through the bulk semiconductor layers.
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 photon extraction efficiency from a single side of the LED while maintaining appropriate current distribution, increasing the number of photons escaping and reducing losses, thus enhancing overall LED performance.
Implementation Method 1
controlling the thickness and conductivity of semiconductor layers to enhance constructive interference
Implementation Method 2
Such texturing makes it possible to limit light reflections inside the stack, and to diffuse this light towards the outside of the stack
Data Source
AI summary
A light-emitting diode includes a stack of semiconductor layers including a first face and a second face that are opposite one another relative to a thickness of the stack, a first electrode including a face in contact with the first face of the stack, and a second electrode in contact with the stack. Moreover, the light-emitting diode is such that a recess is formed in the second face of the stack which results in the stack including a thinned part, the face of the first electrode in contact with the first face is in contact only with the thinned part of the stack, and the second electrode is in contact with a zone of the stack separate from the thinned part of the stack.