Infrared LED InGaAs Cladding Layer Current Spreading
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Solution Overview
Problem
Infrared light-emitting diodes with AlGaAs cladding layers face issues of poor current spreading and low antistatic resistance due to the high reactivity and oxidizability of Al atoms, leading to inefficient light emission and reliability concerns.
Innovation Solution
The use of low-band gap cladding layers made of GaAs or InxGa1-xAs, which have lower resistivity and are less prone to oxidation, improves current conduction and light-emitting efficiency by replacing the AlGaAs material, and a multi-quantum well structure is employed to achieve lattice matching and reduce dislocation defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If AlGaAs material is used in the cladding layer, then the light-emitting peak wavelength can be above 900 nm, but the current spreading is poor and antistatic resistance is low due to high resistivity and easy oxidation of Al atoms
Solution Approach 1:
The patent changes the material composition parameter by replacing AlGaAs with InGaAs, adjusting the In component ratio (0%≤x≤5%) to achieve the desired wavelength while improving electrical properties. This parameter change resolves the contradiction by selecting a material composition that simultaneously provides the required optical performance and enhanced reliability through lower resistivity and oxidation resistance
Solution Approach 2:
The patent uses composite material structure with InxGa1-xAs cladding layer combined with specific active layer compositions to achieve both the wavelength requirement and improved current spreading. The composite approach allows optimization of both optical and electrical characteristics that cannot be achieved with a single material system
2Illumination intensity
If AlGaAs material is used in the cladding layer, then the structure can support infrared emission, but the light-emitting efficiency is low due to poor current spreading
Solution Approach 1:
The patent changes the electrical parameter of the cladding layer by substituting AlGaAs with InGaAs, which has inherently lower resistivity. This parameter change improves horizontal current conduction and spreading, directly addressing the productivity issue while maintaining the light-emitting function
Solution Approach 2:
The patent replaces the problematic AlGaAs material with InGaAs material that has better electrical properties. Although InGaAs may have different cost characteristics, it provides superior current spreading and light-emitting efficiency, effectively replacing the inferior material to achieve better overall performance
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 configuration enhances light-emitting efficiency, reduces voltage, and eliminates the 'red dot effect' by blocking visible light, while providing improved antistatic resistance and reliability in infrared light-emitting diodes.
Implementation Method 1
GaAs or InGaAs has low resistivity and is free of easy-oxidized Al component, which can improve horizontal conduction of current and show good current spreading effect if applied in the cladding layer
Implementation Method 2
GaAs and InGaAs materials have low energy gap and low resistivity... GaAs and InGaAs materials can block visible light from being emitted from the component, appearing no weak red light when the component is lighted on
Implementation Method 3
an active layer, wherein, the active layer is (InxGa1-X)As or (AlX1Ga1-X1)Y1In1-Y1As
Data Source
AI summary
An infrared light-emitting diode includes, from up to bottom, a P-type ohmic electrode, a contact layer, a P-type cladding layer, an active layer, an N-type cladding layer, a buffer layer, a GaAs substrate and an N-type ohmic electrode. The N-type cladding layer and the P-type cladding layer or either of them is InxGa1-xAs. The cladding layer of InxGa1-xAs, due to low resistance, can improve current expansion, reduce voltage and improve light-emitting efficiency.