Resonant Cavity LED Structure for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting devices face limitations in external light emission efficiency due to total reflection at the interface between semiconductor layers and air or background materials, restricting the output of light.
Innovation Solution
The implementation of a resonant cavity structure, either in the form of a column or hole pattern, is introduced at the upper portion of the light emitting structure, which adjusts current density and enhances light extraction efficiency by utilizing the vertically-directional vibration mode, thereby concentrating light emission in a vertical direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a roughness structure or periodical concave-convex structure is employed for the semiconductor layer interface, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent employs a resonant cavity structure that utilizes vertical vibration modes of light waves to enhance light extraction. By designing the cavity depth and width to match specific wavelengths, the structure creates resonant conditions that amplify light extraction efficiency without requiring complex surface roughness patterns or concave-convex structures.
Solution Approach 2:
The patent changes the geometric parameters of the resonant cavity (depth, width, and position relative to the active layer) to optimize light extraction for specific wavelengths. By adjusting these parameters, the device achieves high extraction efficiency for targeted colors without needing complex multi-scale surface structures.
2Productivity
If a resonant cavity structure is used, then light extraction efficiency and directionality are improved, but device complexity increases
Solution Approach 1:
The patent utilizes the resonant vibration of light waves within a cavity structure. By designing the cavity dimensions to support specific vertical vibration modes, the structure naturally directs light extraction in the vertical direction with enhanced efficiency, eliminating the need for additional optical components or complex surface modifications.
Solution Approach 2:
The patent introduces a vertical dimension to light extraction by creating a cavity that extends downward from the active layer. This vertical cavity structure exploits the third dimension (depth) to control light propagation, achieving directionality and enhanced extraction without complicating the lateral plane structures.
3Productivity
If current density is adjusted to enhance resonant cavity effect, then light extraction efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements a current blocking layer with specific patterns (such as stripes or blocks) that create localized regions of different current density. This allows the device to achieve uniform overall current distribution while maintaining local variations that enhance the resonant cavity effect, reducing the need for extremely precise uniform current control across the entire device.
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 approach significantly improves light extraction efficiency by reducing light confinement due to total reflection and increasing the amount of light emitted vertically, while ensuring the reliability and yield of the fabrication process.
Implementation Method 1
resonant cavity effect may be used likewise a resonant cavity LED... when the resonant cavity effect is used, the direction of the light emitted from the active layer is adjusted through an intrinsic mode of the resonant cavity
Implementation Method 2
the external light emission efficiency refers to the probability of outputting a light from an active layer to the outside of a device, and has a restricted value due to the total reflection caused by the difference in the refractive index between a semiconductor layer and air
Data Source
AI summary
Disclosed are a light emitting device, a light emitting device package, and a lighting system. The light emitting device includes an electrode layer, a current density adjusting pattern on the electrode layer, and a light emitting structure on the electrode layer and the current density adjusting pattern. The light emitting structure includes a second conductive semiconductor layer, an active layer on the second conductive semiconductor layer, and a first conductive semiconductor layer on the active layer. The first conductive semiconductor layer includes an upper portion including a column pattern or a hole pattern serving as a structure of a resonant cavity and a lower portion having a thickness less than a thickness of the upper portion.