Multi-Cell LED Array with Segmented Active Layers
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Solution Overview
Problem
High-power semiconductor LEDs experience low light efficiency due to high current density and heat generation, leading to decreased luminance, which is a challenge for their commercialization as high-efficiency illumination sources.
Innovation Solution
A semiconductor light emitting device with a multi-cell array structure, featuring a substrate with interconnected light emitting cells, insulation layers, and a series-parallel connection configuration, where the first insulation layer is not formed between the electrode and the side surface of the light emitting cell, and the active layer and second conductive semiconductor layer are formed in a U-shape pattern to maximize the active layer area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the current rating of an LED chip is increased to obtain high luminous flux and high power, then the luminous flux and power are improved, but the light efficiency is degraded due to increased current density
Solution Approach 1:
The LED device is divided into multiple light emitting cells (e.g., 9 cells arranged in a 3x3 array) that are connected in series. Each cell has its own active layer and conductive semiconductor layers. This segmentation allows the total power to be distributed across multiple cells, reducing the current density in each individual cell while maintaining high overall power output and light efficiency.
2Power
If the current rating of an LED chip is increased to obtain high luminous flux and high power, then the luminous flux and power are improved, but heat generation increases which accelerates light efficiency degradation
Solution Approach 1:
By dividing the high-power LED into multiple series-connected light emitting cells, the current through each cell is reduced compared to a single high-current cell. This reduces the Joule heating (I²R losses) in each cell, thereby reducing overall heat generation and preventing the thermal runaway that degrades light efficiency.
3Illumination intensity
If the active layer area is widened to improve luminance, then the luminance and light efficiency are improved, but the current density increases which degrades light efficiency
Solution Approach 1:
The total active layer area is distributed across multiple separate light emitting cells rather than concentrated in a single large cell. Each cell has its own active layer with moderate area, allowing the device to achieve high total luminance through the combination of multiple cells while maintaining low current density in each cell, thus preserving light efficiency.
4Reliability
If a first insulation layer is formed to cover the light emitting cell surface, then the insulation and protection are improved, but the active layer area is reduced which decreases luminance
Solution Approach 1:
The insulation structure is designed to cover only the regions between the light emitting cells and not the active layer regions of each cell. This is achieved by forming the first insulation layer to extend between adjacent cells while leaving the active layers exposed, thus providing necessary insulation and protection without reducing the total active layer area available for light emission.
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 enhances luminance and operating voltage by widening the active layer area, thereby improving the light efficiency and power handling capabilities of the semiconductor light emitting device.
Implementation Method 1
each light emitting cell includes a first conductive semiconductor layer and wherein at least a portion of the first conductive semiconductor layer has an active layer and a second conductive semiconductor layer disposed on a top surface thereof
Data Source
AI summary
A semiconductor light emitting device includes a substrate and a plurality of light emitting cells disposed on the substrate. Each light emitting cell includes first and second conductive semiconductor layers having an active layer formed therebetween, and first and second electrodes formed on the first and second layers. A first insulation layer is formed on portions of the light emitting cell, while a second insulation layer entirely covers at least one light emitting cell. A method of manufacturing the semiconductor light emitting device, and a light emitting module and an illumination apparatus including the semiconductor light emitting device are also provided.