Nitride Semiconductor Tunnel Junction Structure for Lower Forward Voltage
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Solution Overview
Problem
Nitride semiconductor elements with tunnel junctions tend to have high forward voltage, which is a limitation in their performance.
Innovation Solution
A nitride semiconductor element is designed with a first and second light emission part, each comprising specific semiconductor layers with varying n-type impurity concentrations and thicknesses, where the second layer has a lower impurity concentration and greater thickness than the first layer, forming a tunnel junction to reduce forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a tunnel junction is formed in a nitride semiconductor layer, then light emission capability is improved, but forward voltage becomes high
Solution Approach 1:
The patent divides the semiconductor structure into multiple light emission parts (first light emission part and second light emission part) separated by n-type impurity layers. This segmentation allows the tunnel junction to be distributed across multiple interfaces rather than concentrated at a single point, reducing the overall forward voltage while maintaining light emission capability from multiple active layers.
Solution Approach 2:
The patent applies different n-type impurity concentrations at different locations: the first and second layers have higher impurity concentrations to form effective tunnel junctions with the p-side semiconductor layer, while the second n-side semiconductor layer has a lower impurity concentration to reduce forward voltage. This local variation in impurity concentration optimizes both light emission and voltage characteristics.
2Illumination intensity
If multiple light emission parts are integrated, then light output is enhanced, but device complexity increases
Solution Approach 1:
The patent merges multiple light emission parts into a single integrated semiconductor element, where the first and second light emission parts are combined with intermediate n-type impurity layers. This merging approach enhances total light output while avoiding the complexity of separate discrete devices, as all components are grown as a unified structure using epitaxial growth methods.
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 design effectively reduces the forward voltage and enhances light output by optimizing the impurity concentrations and layer thicknesses, improving the crystallinity and surface morphology of the nitride semiconductor element.
Implementation Method 1
a first layer that contains an n-type impurity of a first concentration, is formed on the first light emission part, and is in contact with the first p-side semiconductor layer; a second layer that contains an n-type impurity of a second concentration, is formed on the first layer
Data Source
AI summary
A method of manufacturing a nitride semiconductor element includes: providing a first light emission part comprising a first n-side semiconductor layer, a first active layer formed on the first n-side semiconductor layer, and a first p-side semiconductor layer formed on the first active layer; forming a first layer such that the first layer contains an n-type impurity of a first concentration; forming a second layer such that the second layer contains an n-type impurity of a second concentration lower than the first concentration, wherein a thickness of the second layer is greater than a thickness of the first layer; and forming a second light emission part comprising: a second n-side semiconductor layer such that the second n-side semiconductor layer contains an n-type impurity of a third concentration lower than the first concentration and the second concentration, a second active layer, and a second p-side semiconductor layer.