Strained AlGaInP Layers for Carrier Confinement in LEDs
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Solution Overview
Problem
Light-emitting diodes (LEDs) face challenges in achieving efficient electron and hole blocking, particularly at high-temperature and high-current operations, due to carrier escape from the active layer despite the presence of well structures, which affects the device's efficiency and emission wavelength range.
Innovation Solution
The implementation of strained AlGaInP layers, including compressively strained hole blocking layers and tensile-strained electron blocking layers, along with well structures in the active layer, to enhance carrier confinement and prevent carrier overflow, utilizing the (AlxGa1-x)1-yInyP alloy system for improved electron and hole blocking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If well structures are used in the active layer, then carrier confinement is improved, but carrier escape still occurs at high-temperature and high-current operations
Solution Approach 1:
The patent applies strain engineering by changing the physical state of the barrier layers through tensile and compressive strain. The first and second barrier layers are arranged to have tensile strain, while the hole blocking layer has compressive strain. This parameter change modifies the energy band structure to enhance carrier confinement and prevent carrier escape at high-temperature and high-current operations.
Solution Approach 2:
The patent uses composite material structures by combining multiple layers with different strain states and material compositions from the (AlxGa1-x)1-yInyP alloy system. The active layer comprises well structures with strained barrier layers and unstrained barrier layers, creating a composite structure that leverages the complementary properties of each layer to achieve superior carrier confinement.
2Reliability
If strained AlGaInP layers are implemented, then electron and hole blocking capabilities are enhanced, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different strain states to different layers based on their specific functions. The hole blocking layer is given compressive strain optimized for hole blocking, while the barrier layers within the active layer are given tensile strain optimized for electron confinement. Each layer's strain state is locally optimized for its specific blocking or confinement function.
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 significantly enhances carrier confinement and recombination efficiency, improving the light-emitting device's performance at high-temperature and high-current operations while maintaining control over the emission wavelength range.
Implementation Method 1
at least a portion of the hole blocking layer may be arranged to have a compressive strain. Additionally or alternatively, in some implementations, the active layer may be provided with at least one well structure including: a first barrier layer arranged to have a tensile strain, a second barrier layer arranged to have a tensile strain
Implementation Method 2
The implementation of strained AlGaInP layers, including compressively strained hole blocking layers and tensile-strained electron blocking layers, along with well structures in the active layer, to enhance carrier confinement and prevent carrier overflow
Implementation Method 3
The main functional part of an LED can be a semiconductor chip comprising two injecting layers of opposite conductivity types (p-type and n-type), and a light-emitting active layer for radiative recombination in which injection of carriers takes place
Data Source
AI summary
A light-emitting device is disclosed. The light emitting device includes an electron blocking layer, a hole blocking layer, wherein at least a portion of the hole blocking layer is arranged to have a compressive strain, and an active layer disposed between the hole blocking layer and the electron blocking layer. The active layer may include a first barrier layer arranged to have a tensile strain, a second barrier layer arranged to have a tensile strain, and a first well layer disposed between the first barrier layer and the second barrier layer. The active layer may also include a first unstrained barrier layer, a second unstrained barrier layer, and a second well layer disposed between the first unstrained barrier layer and the second unstrained barrier layer.