High-Power Red LED Mg Diffusion Barrier Design
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Solution Overview
Problem
High-power red LEDs experience light output power drop due to magnesium (Mg) diffusion from the GaP window layer into the active region, leading to reliability issues as current increases, causing instability in light output power over time.
Innovation Solution
Incorporating a second conductive GaP layer with a lower concentration and a second conductive GaP layer with a higher concentration on the second conductive clad layer to trap diffused Mg, forming an Mg-free region and ensuring stable light output power over extended operation and life time tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high current is applied to increase power output, then light output power increases, but magnesium diffusion into the active region occurs causing light output power drop
Solution Approach 1:
A GaP layer is introduced as an intermediary barrier between the AlGaInP window layer and the active region. This GaP layer prevents magnesium atoms from diffusing into the active region while allowing the high current to pass through, thus maintaining both high power output and light output stability over time
Solution Approach 2:
The magnesium-containing window layer is separated from the active region by extracting the problematic interface and replacing it with a GaP layer. This removes the source of magnesium diffusion while preserving the electrical functionality of the 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
The solution effectively prevents light output power drop, maintaining light output within ±10% of the initial level after 65 or 165 hours, thereby enhancing the reliability of high-power red LEDs.
Implementation Method 1
magnesium (Mg) diffusion from the GaP window layer into the active region
Implementation Method 2
Incorporating a second conductive GaP layer with a lower concentration and a second conductive GaP layer with a higher concentration on the second conductive clad layer to trap diffused Mg
Implementation Method 3
A light emitting device includes a P-N junction diode having a characteristic of converting electrical energy into light energy. When forward voltage is applied to the LED, electrons of an N layer are combined with holes of a P layer, so that energy corresponding to an energy gap between a conduction band and a valance band may be generated. The energy is mainly emitted in the form of heat or light. In the case of the LED, the energy is generated in the form of light.
Data Source
AI summary
Disclosed are a light emitting device, a method of fabricating the light emitting device, a light emitting device package, and a lighting system. The light emitting device includes a first conductive semiconductor layer (130), an AlGaInP-based active layer (140) on the first conductive semiconductor layer (130), a second conductive clad layer (150) on the AlGaInP-based active layer (140), a second conductive GaP layer (162) having first concentration on the second conductive clad layer (150), and a second conductive GaP layer (164) having second concentration higher than the first concentration on the second conductive GaP layer (162) having the first concentration.