InGaN LED Active Region with Low-Indium Barrier Layers
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Solution Overview
Problem
Current light-emitting diodes (LEDs) with InGaN well layers and GaN barrier layers face issues such as carrier overflow and piezoelectric polarization, leading to efficiency droop and reduced performance at higher current densities.
Innovation Solution
The semiconductor structure includes an active region with InGaN well layers and InGaN barrier layers, optimized to reduce piezoelectric polarization and enhance carrier confinement, featuring a specific composition and layer configuration to improve light-emitting device efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GaN barrier layers are used with InGaN well layers, then carrier confinement is improved, but piezoelectric polarization increases leading to efficiency droop
Solution Approach 1:
The patent changes the material composition parameter by replacing GaN barrier layers with InGaN barrier layers having lower indium content (0.01≤b≤0.10) than the well layers (0.10≤w≤0.40). This parameter change reduces the piezoelectric polarization effect while maintaining the necessary band offset for carrier confinement, thereby resolving the contradiction between improved carrier confinement and reduced efficiency droop.
Solution Approach 2:
The patent employs a composite structure where InGaN well layers are combined with InGaN barrier layers of different indium compositions. This composite material approach allows optimization of both carrier confinement (through the heterostructure) and polarization reduction (through compositional grading), simultaneously addressing both requirements without using pure GaN barriers.
2Illumination intensity
If higher current densities are applied to increase light output, then illumination intensity improves, but efficiency droop increases due to carrier overflow and polarization
Solution Approach 1:
The patent modifies the compositional parameters of the barrier layers (lower indium content ranging from 0.01 to 0.10) to reduce piezoelectric polarization. This enables the device to maintain higher internal quantum efficiency at elevated current densities, allowing increased light output without proportional efficiency loss.
Solution Approach 2:
The patent applies different indium compositions to different layers: higher indium content (0.10≤w≤0.40) in well layers for strong carrier confinement and lower indium content (0.01≤b≤0.10) in barrier layers for reduced polarization. This local quality differentiation allows the structure to handle higher current densities more efficiently by minimizing polarization-related losses in the barrier regions.
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 results in improved internal quantum efficiency and reduced efficiency droop across a range of current densities, maintaining high performance even at higher injection levels.
Implementation Method 1
an active region with InGaN well layers and InGaN barrier layers, optimized to reduce piezoelectric polarization and enhance carrier confinement
Implementation Method 2
optimized to reduce piezoelectric polarization and enhance carrier confinement, featuring a specific composition and layer configuration to improve light-emitting device efficiency and uniformity
Implementation Method 3
As the electrons and holes recombine within the active region of the LED, energy is released in the form of photons, which are emitted from the active region of the LED
Data Source
AI summary
Semiconductor structures include an active region between a plurality of layers of InGaN. The active region may be at least substantially comprised by InGaN. The plurality of layers of InGaN include at least one well layer comprising InwGa1−wN, and at least one barrier layer comprising InbGa1−bN proximate the at least one well layer. In some embodiments, the value of w in the InwGa1−wN of the well layer may be greater than or equal to about 0.10 and less than or equal to about 0.40 in some embodiments, and the value of b in the InbGa1−bN of the at least one barrier layer may be greater than or equal to about 0.01 and less than or equal to about 0.10. Methods of forming semiconductor structures include growing such layers of InGaN to form an active region of a light-emitting device, such as an LED. Luminary devices include such LEDs.