Parabolic Vertical Micro-LED for High Pixel Density
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Solution Overview
Problem
Current light emitting diodes (LEDs) face challenges in reducing size while maintaining electrical and optical performance, particularly in achieving effective light collimation and extraction efficiency, which limits pixel density in displays.
Innovation Solution
The development of a micro-LED with an epitaxial structure featuring a mesa with a truncated top and a cylindrical top portion, including quantum wells positioned at a parabolic focal point, and a reflective contact to enhance light collimation and extraction efficiency by reflecting light back towards the light emitting surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of LEDs is decreased to improve pixel density, then pixel density increases, but light extraction efficiency and electrical performance deteriorate
Solution Approach 1:
The patent employs a parabolic curved surface structure in the LED device. The parabolic shape is designed with its focal point positioned at the quantum well layer, creating a curved reflective surface that optimizes light extraction. This curvature allows light generated in the quantum wells to be reflected and directed outward more efficiently, maintaining high light extraction efficiency even in miniaturized LED structures where conventional flat designs would fail.
2Reliability
If structures are added to reflect and collimate light, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into a single unified structure. The parabolic curved surface simultaneously serves as both a reflective surface and a collimating element. By combining these two light management functions into one geometric feature rather than using separate components, the design achieves high light extraction efficiency while minimizing structural complexity and maintaining manufacturability.
3Reliability
If effective light collimation is implemented, then light extraction efficiency improves, but the types and sizes of structures are constrained
Solution Approach 1:
The patent utilizes the optical parameter of the parabolic geometry, specifically positioning the focal point of the parabola at the quantum well layer. This parameter optimization enables the curved surface to naturally collimate and direct light without requiring additional complex structural elements. The focal point positioning creates an optimal optical path that achieves effective light collimation while maintaining flexibility in device design and manufacturing.
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 design allows for thicker epitaxial layers, improved electrical performance, and increased light extraction efficiency, enabling smaller LED sizes and enhanced brightness while maintaining desirable optical properties.
Implementation Method 1
reflected by the reflective contact back through the top portion and the mesa in second directions toward the light emitting surface
Implementation Method 2
one or more quantum wells within the mesa to emit light
Data Source
AI summary
A micro-light emitting diode (LED) includes an epitaxial structure having a mesa and a top portion on the mesa. The epitaxial structure further includes quantum wells within the mesa configured to emit light, claddings surrounding the quantum wells, and a light emitting surface on a side opposite the mesa and top portion. A reflective contact is on the top portion of the epitaxial structure. Light emitted from the quantum wells are transmitted through the mesa and the top portion in first directions, and reflected by the reflective contact back through the top portion and the mesa in second directions toward the light emitting surface. The top portion allows the quantum wells to be positioned at a parabola focal point of the mesa without limiting cladding thickness.