Micro-LED Mesa Structure with Parabolic Reflector and Index-Matched Coating
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Solution Overview
Problem
Micro-LEDs have lower light extraction efficiency compared to large-power LEDs, with typical light extraction efficiency ranging from 10% to 0.5% within specific emission cones, limiting their application in display technology due to inefficient light directionality and beam profile.
Innovation Solution
The design incorporates a mesa-shaped semiconductor layer with a reflector layer and secondary optics, including an index-matched material and anti-reflection coatings, to enhance light extraction efficiency and achieve a narrower beam profile, with specific configurations such as parabolic and conical shapes to improve light directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If micro-LEDs use conventional planar or hemispherical structures, then manufacturing is simpler, but light extraction efficiency is low (10% within 90° emission cone)
Solution Approach 1:
The patent applies spheroidality by transforming the conventional planar or hemispherical LED structure into a parabolic shape. The parabolic reflector geometry focuses and redirects light emitted from the LED chip, converting omnidirectional emission into a directed beam. This curved geometric transformation enables the micro-LED to achieve high light extraction efficiency (85% within 90° emission cone) while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
2Illumination intensity
If micro-LEDs emit light in wide angles (90° emission cone), then light coverage is broader, but beam profile is too wide for focused applications
Solution Approach 1:
The patent applies parameter changes by modifying the emission cone angle and beam profile through the parabolic geometric configuration. The parabolic shape parameters (focal length, depth, width) are optimized to control light redirection, achieving a focused beam profile with 85% light extraction efficiency within a 90° emission cone. This geometric parameter optimization enables the micro-LED to maintain broad light coverage while producing a focused, directional beam suitable for display applications.
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 significantly increases light extraction efficiency to between 50% and 85% within a 90° emission cone and 2% to 6% within a 10° cone, providing a more focused and efficient light output for micro-LEDs.
Implementation Method 1
The light emitting diode also includes a first anti-reflection coating adjacent to the outcoupling surface
Implementation Method 2
an index-matched material between the outcoupling surface and the optical element, wherein an index of refraction of the index-matched material is greater than or equal to an index of refraction of the optical element
Implementation Method 3
The light emitting diode also includes a reflector layer on an outer surface of the mesa shape
Data Source
AI summary
Disclosed herein are light emitting diodes (LEDs) having a high efficiency. A light emitting diode including an active light emitting layer within a semiconductor layer is provided. The semiconductor layer has a mesa shape. The light emitting diode also includes a substrate having a first surface on which the semiconductor layer is positioned and an outcoupling surface opposite to the first surface. Light generated by the active light emitting layer is incident on the outcoupling surface and propagates toward an optical element downstream of the outcoupling surface. The light emitting diode also includes a first anti-reflection coating adjacent to the outcoupling surface; an index-matched material between the outcoupling surface and the optical element, wherein an index of refraction of the index-matched material is greater than or equal to an index of refraction of the optical element; and/or secondary optics adjacent to the outcoupling surface.