AlGaInP Window Layer LED for Light Extraction and Current Spreading
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Solution Overview
Problem
The current methods for transferring quaternary aluminum gallium indium phosphorus epitaxial layers to silicon substrates result in light emission being blocked by electrodes, leading to reduced light extraction efficiency and current crowding issues due to vertical current conduction and light absorption by GaAs n-side electrode window layers.
Innovation Solution
Incorporating an aluminum gallium indium phosphorus window layer as an ohmic contact layer for the first conductive semiconductor layer, with a first electrode connected to this layer, and a second electrode connected to the second conductive semiconductor layer, ensuring the electrodes are positioned opposite the light-emitting side to minimize light blocking and facilitate horizontal current spreading through low-resistance regions formed by metal diffusion or ion implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GaAs is used as the n-side electrode window layer, then ohmic contact is achieved, but light absorption occurs at the light-emitting side resulting in light loss
Solution Approach 1:
The patent changes the material composition of the window layer from GaAs to aluminum gallium indium phosphorus (AlGaInP) with specific compositional parameters (Al content 0.3-0.8, In content 0.05-0.3). This material substitution maintains the ohmic contact function while significantly reducing light absorption in the red light-emitting range, thereby resolving the contradiction between contact quality and light loss.
2Loss of energy
If electrode size is reduced to minimize light blocking, then light extraction efficiency improves, but current crowding and high voltage occur
Solution Approach 1:
The patent optimizes the thickness parameter of the AlGaInP window layer to 2-6 μm. This specific thickness range allows the electrode to maintain sufficient size for uniform current distribution while minimizing light blocking, as the optimized thickness balances electrical conductivity with optical transparency in the red light spectrum.
3Device complexity
If vertical current conduction is used, then simple device structure is achieved, but current crowding and high voltage occur
Solution Approach 1:
The patent introduces lateral current spreading capability in the AlGaInP window layer through optimized material composition and thickness. This creates different current conduction characteristics in different regions: vertical conduction dominates in areas needing simple structure, while lateral spreading occurs in regions requiring uniform current distribution, effectively resolving the contradiction between structural simplicity and current uniformity.
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
Enhances light extraction efficiency by reducing electrode shadowing and current crowding, allowing for improved luminous efficiency and uniform current distribution, suitable for high-end lighting and display applications.
Implementation Method 1
an aluminum gallium indium phosphorus window layer as an ohmic contact layer forming contact between the first electrode and the first conductive type semiconductor layer
Implementation Method 2
horizontal current spreading through low-resistance regions formed by metal diffusion or ion implantation
Implementation Method 3
horizontal current spreading through low-resistance regions formed by metal diffusion or ion implantation
Data Source
AI summary
A semiconductor light-emitting device includes a semiconductor light-emitting sequence which includes a first conductive type semiconductor layer, a second conductive type semiconductor layer and a light-emitting layer therebetween, a first electrode electrically connected to the first conductive type semiconductor layer, and a second electrode electrically connected to the second conductive type semiconductor layer. The first conductive type semiconductor layer includes an aluminum gallium indium phosphorus window layer as an ohmic contact layer forming contact between the first electrode and the first conductive type semiconductor layer.