Invisible-Light LED GaAs Absorption Layer Red Dot Effect
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Solution Overview
Problem
Conventional invisible-light light-emitting diodes suffer from the 'red dot effect' due to excessive light absorption, leading to reduced light power and inability to produce high-brightness chips, which are inadequate for security and protection systems.
Innovation Solution
A high-brightness invisible-light light-emitting diode is developed with a GaAs visible-light absorption layer, specific cladding layers, and a current spreading layer, optimized to minimize visible light emission, featuring a band gap difference of 0.13 eV and a thickness below 100 nm for the absorption layer, and a current density of ≥1 A/mm² to achieve a visible light ratio <0.2%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light absorption layer with thickness above 0.1 μm is used to reduce visible light, then visible light ratio decreases, but light power output sharply reduces
Solution Approach 1:
The patent optimizes the thickness parameter of the light absorption layer to be between 30-100 nm (0.03-0.1 μm), which is significantly thinner than conventional designs (>0.1 μm). This parameter optimization achieves visible light suppression while preserving sufficient infrared light power output, resolving the contradiction between visible light reduction and power maintenance
Solution Approach 2:
The patent uses a composite structure consisting of a light absorption layer with specific band gap characteristics combined with an active layer. The light absorption layer has a band gap wider than the active layer, creating a selective filtering effect that absorbs visible light while transmitting infrared light, thereby resolving the contradiction between visible light suppression and infrared power output
2Object-affected harmful factors
If conventional infrared LED structure is used to suppress visible light, then red dot effect is reduced, but high-brightness requirement cannot be met
Solution Approach 1:
The patent optimizes multiple parameters including light absorption layer thickness (30-100 nm), band gap difference (0.13 eV), and doping concentration to achieve both red dot elimination and high brightness. The optimized parameters enable the device to meet security system requirements for both purity and intensity
Solution Approach 2:
The patent employs a composite epitaxial structure with specific material composition and layer configuration. The combination of light absorption layer and active layer with optimized band gap difference creates a structure that simultaneously achieves visible light suppression and high infrared brightness, resolving the contradiction between red dot reduction and brightness requirement
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 eliminates visible light emission, enhancing light power output and enabling the production of high-brightness chips suitable for security and protection systems by reducing the red dot effect.
Implementation Method 1
a GaAs visible-light absorption layer... band gap difference between the GaAs visible-light absorption layer and the light-emitting layer is 0.13 eV
Implementation Method 2
light-emitting layer... when input current density of the light-emitting layer is ≥1 A/mm2, visible light ratio of the light-emitting diode is <0.2%
Data Source
AI summary
An invisible-light light-emitting diode includes an N-type ohmic contact semiconductor layer, an N-type current spreading layer, an N—GaAs visible-light absorption layer, an N-type cladding layer, a light-emitting layer, a P-type cladding layer and a P-type ohmic contact semiconductor layer. In the invisible-light light-emitting diode, the absorption layer is GaAs, which can effectively remove all visible light when current density is >1 A/mm2, and essentially all visible light when current density is below 3 A/mm2. This effectively solves the red dot effect of invisible-light light-emitting diodes.