Flip-Chip Light Emitting Element With Color-Specific Interference Control
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Solution Overview
Problem
Conventional light emitting elements using interference to amplify light emission emit monochromatic light and lack control over interference for multiple colors, specifically blue, green, and red light, which are typically stacked on the same substrate.
Innovation Solution
A flip-chip type light emitting element with multiple active layers of different emission colors, where the interference of light is controlled by adjusting the thicknesses of specific layers and electrodes, allowing for amplification of at least one color's light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple active layers emitting different colors are stacked on the same substrate, then full-color emission capability is improved, but control over interference for each color becomes difficult
Solution Approach 1:
The device segments the interference control for each color by providing separate p layers (first p layer and second p layer) and separate reflective electrodes (first p electrode and second p electrode) for each active layer. This allows independent thickness adjustment and interference control for blue, green, and red light emissions without affecting other colors.
Solution Approach 2:
Each p layer and reflective electrode combination is locally optimized for its corresponding active layer's emission wavelength. The first p layer and first p electrode are optimized for blue light, the second p layer and second p electrode for green light, enabling each region to have the specific optical properties needed for its function.
2Illumination intensity
If interference is used to amplify light emission, then light emission intensity is improved, but the structure becomes more complex requiring precise thickness control
Solution Approach 1:
The patent utilizes parameter changes by adjusting the thicknesses of p layers and reflective electrodes to control optical interference. By varying these dimensional parameters, constructive interference is achieved at specific wavelengths to amplify light emission intensity for each color channel.
3Ease of operation
If separate control structures are provided for each color, then interference control for each color is improved, but device structure becomes more complex
Solution Approach 1:
The p layers and reflective electrodes serve multiple functions: they provide electrical contact for carrier injection, form part of the optical cavity for interference control, and act as reflective surfaces for light extraction. This multi-functionality reduces the need for separate dedicated control structures for each color.
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 enables separate control and amplification of light interference for each color, enhancing the light emitting element's efficiency and capability to produce full-color emissions with reduced production costs.
Implementation Method 1
a first p electrode that is provided over the first p layer and is configured to reflect light; and a second p electrode that is provided over the second p layer and is configured to reflect light
Implementation Method 2
light emitted from the second active layer causes interference between light directed toward the substrate and light directed toward the first p electrode and reflected by the first p electrode
Data Source
AI summary
In a light emitting element, light emitted from the second active layer causes interference between light directed toward the substrate and light directed toward the first p electrode and reflected by the first p electrode, and the interference is controlled based on a thickness a1 of the first p layer, light emitted from the first active layer causes interference between the light directed toward the substrate and light directed toward the second p electrode and reflected by the second p electrode, and the interference is controlled based on a thickness a2 of the second p layer and a thickness b of a region in the non-doped layer where the groove is formed, and the thicknesses a1, a2, and b are set such that at least one of the light emitted from the first active layer or the light emitted from the second active layer is amplified by the interference.