InGaAs/GaAsP Quantum Well Structure for Long-Wavelength IR LEDs
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Solution Overview
Problem
GaAs-based infrared LEDs with wavelengths greater than 1000 nm suffer from low light-emitting efficiency and poor reliability due to lattice mismatches between the active layer and the substrate, which is not adequately addressed by existing technologies.
Innovation Solution
A semiconductor epitaxial structure with quantum well layers made of InxGa1-xAs and quantum barrier layers made of GaAs1-yPy, where 0.2≤x≤0.3 and 0≤y≤0.05, is used to reduce compressive stress caused by lattice mismatches, improving the light-emitting efficiency and reliability of infrared LEDs with a wavelength of 1050 nm±50 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GaAs-based LED structure is used for wavelength greater than 1000 nm, then the wavelength requirement is met, but light-emitting efficiency and reliability deteriorate due to lattice mismatch
Solution Approach 1:
The patent changes the material composition parameters by introducing InGaAs quantum well layers with specific In content (x=0.2-0.3) and GaAsP quantum barrier layers with controlled P content (y=0.02-0.05). This parameter optimization reduces lattice mismatch while maintaining the desired wavelength >1000 nm, thereby improving both light-emitting efficiency and reliability
Solution Approach 2:
The patent employs a composite quantum well structure combining InGaAs and GaAsP materials. The InGaAs quantum well layers provide the necessary bandgap for long-wavelength emission, while the GaAsP quantum barrier layers with phosphorus doping reduce compressive stress and improve crystal quality, achieving synergistic effect that overcomes the limitations of single-material systems
2Reliability
If thicker quantum barrier layers are used to reduce compressive stress, then reliability improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by selectively doping phosphorus only in the quantum barrier layers (GaAsP) while keeping the quantum well layers (InGaAs) undoped or differently doped. This localized modification optimizes stress distribution precisely where needed without complicating the entire device structure, maintaining simplicity while improving reliability
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 proposed structure effectively reduces compressive stress and enhances the brightness and reliability of infrared LEDs with a wavelength of 1050 nm±50 nm, overcoming the limitations of prior art by using thicker quantum barrier layers and specific material ratios to achieve improved epitaxial quality and light-emitting performance.
Implementation Method 1
A GaAs-based LED having a wavelength greater than 1000 nm may have issues such as low light-emitting efficiency and poor reliability due to massive mismatches between its active layer and a GaAs substrate
Implementation Method 2
Each of the quantum well layers includes a material that is represented by InxGa1-xAs, and each of the quantum barrier layers includes a material that is represented by GaAs1-yPy, where 0.2≤x≤0.3, and 0≤y≤0.05
Data Source
AI summary
A light-emitting device includes a semiconductor epitaxial structure that has a first surface and a second surface opposite to the first surface. The semiconductor epitaxial structure includes a first-type semiconductor layered unit, an active layer, and a second-type semiconductor layered unit sequentially disposed in such order in a direction from the first surface to the second surface. The active layer includes quantum well layers and quantum barrier layers stacked alternately, each of the quantum well layers includes a material that is represented by InxGa1-xAs, and each of the quantum barrier layers includes a material that is represented by GaAs1-yPy, where 0.2≤x≤0.3, and 0≤y≤y0.05.