Monolithic White Light Emitting Device via Wafer Bonding
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Solution Overview
Problem
Conventional white light emitting devices using fluorescent substances suffer from decreased light efficiency and poor color correction, making it difficult to achieve excellent color rendering and are not easily miniaturizable due to the complexity of driving circuits required for combining multiple LEDs.
Innovation Solution
A monolithic white light emitting device is created by bonding multiple emitters as a single chip via wafer or metal bonding, utilizing a conductive submount substrate with a p-type nitride semiconductor layer, active layers, and an n-type AlGaInP-based semiconductor layer to generate light of different wavelengths, allowing for independent control of each emitter and improved light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluorescent substance is used to convert blue light to white light, then white light emission is achieved, but light efficiency and color rendering are degraded
Solution Approach 1:
The patent combines multiple LED emitters (blue LED and green LED) into a single integrated device structure, where each emitter directly generates its characteristic wavelength without requiring fluorescent conversion. This merging of multiple light sources into one chip eliminates the energy loss associated with fluorescent substance conversion while achieving white light emission through direct synthesis of multiple wavelengths.
Solution Approach 2:
The invention extracts and eliminates the fluorescent substance from the light generation system. Instead of using fluorescent material to convert blue light to white light, the patent directly integrates multiple LED emitters that generate their respective wavelengths independently, removing the intermediate conversion step that causes energy loss and maintaining high light efficiency throughout the system.
2Illumination intensity
If multiple separate LEDs are combined to create white light, then white light emission is achieved, but device complexity and miniaturization are hindered
Solution Approach 1:
The patent merges multiple LED emitters (blue LED with wavelength 430-470nm and green LED with wavelength 500-560nm) into a single integrated device structure with shared substrate and electrode system. This integration allows multiple light sources to be controlled through a unified driving circuit rather than requiring separate control circuits for each LED, thereby reducing overall device complexity while enabling white light emission.
Solution Approach 2:
The integrated device structure serves multiple functions simultaneously: it generates blue light, green light, and their combination (white light) through a single unified platform. The shared substrate, electrode, and control system enable this multi-functional operation, eliminating the need for separate driving circuits for each wavelength and facilitating miniaturization.
3Illumination intensity
If fluorescent substance is used for white light generation, then white light emission is achieved, but color correction and rendering are poor
Solution Approach 1:
The patent combines blue LED emission (430-470nm) and green LED emission (500-560nm) in a controlled integrated structure to produce white light with improved color rendering. By directly combining specific wavelength ranges from multiple LED types rather than relying on fluorescent conversion, the system achieves better color correction and rendering characteristics while maintaining efficient light generation.
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 eliminates the need for fluorescent substances, enhancing light efficiency and color rendering while simplifying the device structure, enabling miniaturization and independent control of the emitters for improved white light emission.
Implementation Method 1
blue light is generated from the InGaN-based blue LED 9
Implementation Method 2
blue light is wavelength-converted into white light via a YAG fluorescent substance. blue light excites the Yittrium Aluminum Garnet (YAG) fluorescent substance to finally emit white light
Implementation Method 3
the second light emitter including a p-type AlGaInP-based semiconductor layer, a second active layer and an n-type AlGaInP-based semiconductor layer
Implementation Method 4
a plurality of emitters are bonded as a single chip via wafer bonding or metal bonding
Implementation Method 5
a plurality of emitters are bonded as a single chip via wafer bonding or metal bonding
Data Source
AI summary
The invention relates to a monolithic white light emitting device using wafer bonding or metal bonding. In the invention, a conductive submount substrate is provided. A first light emitter is bonded onto the conductive submount substrate by a metal layer. In the first light emitter, a p-type nitride semiconductor layer, a first active layer, an n-type nitride semiconductor layer and a conductive substrate are stacked sequentially from bottom to top. In addition, a second light emitter is formed on a partial area of the conductive substrate. In the second light emitter, a p-type AlGaInP-based semiconductor layer, an active layer and an n-type AlGaInP-based semiconductor layer are stacked sequentially from bottom to top. Further, a p-electrode is formed on an underside of the conductive submount substrate and an n-electrode is formed on a top surface of the n-type AlGaInP-based semiconductor layer.