Lateral P-Type Extensions for Uniform Carrier Injection in III-Nitride Quantum Wells
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Solution Overview
Problem
III-nitride light emitting devices experience a decrease in internal quantum efficiency at high current density due to nonradiative recombination, particularly because holes do not readily diffuse in p-type III-nitride layers, leading to uneven carrier distribution among quantum wells.
Innovation Solution
The active region of the light emitting device includes p-type extensions that protrude into the active region, allowing for direct, lateral injection of carriers into individual quantum wells, thereby reducing carrier density near the p-type region and minimizing nonradiative recombination by ensuring uniform carrier distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional vertical current injection is used in III-nitride light emitting devices, then the device structure is simple, but internal quantum efficiency decreases at high current density due to nonradiative recombination
Solution Approach 1:
The patent transitions from conventional vertical current injection to lateral current injection by extending the p-type contact layer laterally along the quantum wells. This dimensional change allows carriers to be injected sideways into the active region, improving hole distribution and reducing nonradiative recombination at high current densities while maintaining structural simplicity
2Object-generated harmful factors
If p-type layers are used in III-nitride devices, then the device can achieve light emission, but holes do not readily diffuse in p-type layers leading to uneven carrier distribution
Solution Approach 1:
The patent extends the p-type contact layer laterally along the quantum wells, creating a lateral injection path. This allows holes to diffuse laterally along the extended p-type layer and enter the quantum wells from the side, achieving more uniform carrier distribution across the active region
Solution Approach 2:
The extended p-type contact layer acts as an intermediary structure that facilitates hole transport. It serves as a lateral highway for hole diffusion, allowing carriers to reach the quantum wells more uniformly and reducing the harmful effect of poor hole diffusion in conventional p-type layers
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 design enhances the internal quantum efficiency by reducing carriers lost to nonradiative processes, maintaining efficiency at high current densities through uniform carrier distribution across quantum wells.
Implementation Method 1
holes do not readily diffuse in p-type III-nitride layers, leading to uneven carrier distribution among quantum wells
Data Source
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AI summary
A semiconductor light emitting device includes an active region, an n-type region, and a p-type region comprising a portion that extends into the active region. The active region may include multiple quantum wells separated by barrier layers, and the p-type extension penetrates at least one of the quantum well layers. The extensions of the p-type region into the active region may provide uniform filling of carriers in the individual quantum wells of the active region by providing direct current paths into individual quantum wells. Such uniform filling may improve the operating efficiency at high current density by reducing the carrier density in the quantum wells closest to the bulk p-type region, thereby reducing the number of carriers lost to nonradiative recombination.