III Nitride Semiconductor Light-Emitting Device P-Type Contact Layer
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Solution Overview
Problem
III nitride semiconductor light-emitting devices, particularly those with high-Al-content AlGaN, face limitations in lifetime despite advancements in light emission efficiency, as existing methods often compromise crystallinity and electron blocking functionality.
Innovation Solution
A method involving a p-type contact layer with a two-layer structure is introduced, where the first p-type contact layer is formed using a nitrogen-rich carrier gas directly on the electron blocking layer, and the second p-type contact layer is formed using a hydrogen-rich carrier gas, without a p-type cladding layer, to enhance crystallinity and extend device lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a p-type cladding layer is provided between the electron blocking layer and p-type contact layer, then the light emission efficiency is improved, but the device lifetime is reduced due to degradation of crystallinity
Solution Approach 1:
The patent removes the p-type cladding layer from the device structure, extracting the problematic component that caused crystallinity degradation. The electron blocking layer is made to directly contact the p-type contact layer, eliminating the source of lifetime reduction while maintaining acceptable light emission efficiency through optimized electron blocking layer properties.
Solution Approach 2:
The patent modifies the parameters of the electron blocking layer, specifically increasing the Al content to higher than that of the barrier layer, and optimizing its thickness to 5 nm or more. These parameter changes enable the electron blocking layer to perform both electron blocking and provide a stable interface for the p-type contact layer, compensating for the removed cladding layer's functions.
2Use of energy by moving object
If the Al content of the electron blocking layer is increased to improve electron blocking capability, then the light emission efficiency is improved, but the crystallinity and lifetime are degraded
Solution Approach 1:
The patent optimizes the Al content parameter of the electron blocking layer to be higher than that of the barrier layer, and sets the thickness to 5 nm or more. These parameter changes achieve the right balance between electron blocking capability and crystallinity maintenance, enabling high light emission efficiency without sacrificing device reliability.
Solution Approach 2:
The patent creates a composite structure where the electron blocking layer with high Al content directly contacts the p-type contact layer. This composite interface design allows the high-Al electron blocking layer to provide both electron blocking and crystallinity stabilization functions, preventing the degradation that would normally occur with a separate cladding layer.
3Duration of action of stationary object
If a two-layer p-type contact layer structure is formed to improve lifetime, then the device lifetime is improved, but the manufacturing complexity is increased
Solution Approach 1:
The patent divides the p-type contact layer into two layers with different Al contents: a first p-type contact layer with lower Al content (0.05≤x1<0.2) and a second p-type contact layer with higher Al content (0.2≤x2<0.35). This segmentation allows each layer to perform optimized functions - the first layer provides good carrier injection while the second layer enhances electron blocking and crystallinity stability, achieving improved lifetime through functional division.
Solution Approach 2:
The patent applies local quality by giving different Al content compositions to different parts of the p-type contact layer structure. The first layer has lower Al content optimized for carrier injection at the contact interface, while the second layer has higher Al content optimized for electron blocking and crystallinity protection at the outer interface, with each layer's properties locally optimized for its specific 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 approach significantly improves the lifetime of III nitride semiconductor light-emitting devices by maintaining crystallinity and electron blocking efficiency, leading to enhanced light emission characteristics and prolonged device performance.
Implementation Method 1
supplying at least a carrier gas containing nitrogen as a main component to a surface of the electron blocking layer to expose the surface of the electron blocking layer to the nitrogen containing atmosphere
Implementation Method 2
forming a second p-type contact layer made of AlyGa1-yN, where y satisfies 0≤y≤0.1 on the electron blocking layer after the nitrogen carrier gas supply step using a carrier gas containing hydrogen as a main component
Data Source
AI summary
Provided is a method of producing a III nitride semiconductor light-emitting device having an n-type semiconductor layer, a light emitting layer, a barrier layer, and a p-type semiconductor layer. The p-type semiconductor layer is formed by forming an electron blocking layer on the light emitting layer; supplying a carrier gas containing nitrogen to a surface of the electron blocking layer; and forming a second p-type contact layer made of AlyGa1-yN on the electron blocking layer after the nitrogen carrier gas supply step. The second p-type contact formation step is performed using a carrier gas containing hydrogen. Source gases of Al and Ga are supplied to form a first p-type contact layer made of AlxGa1-xN with a thickness of more than 0 nm and 30 nm or less directly on the electron blocking layer and directly under the second p-type contact layer.