Nitride Semiconductor Light Emitting Device Multi-Layered Structure
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Solution Overview
Problem
Nitride semiconductor light emitting devices face challenges in achieving high light emission output while maintaining low forward voltage (Vf) due to dislocations and defects in the n-type contact layer, which complicates the manufacturing process and increases costs.
Innovation Solution
A nitride semiconductor light emitting device with a multi-layered nitride semiconductor structure, comprising a first nitride semiconductor layer with a high n-type impurity concentration and a second undoped or low n-type impurity concentration layer, stacked in contact with the active layer, grown using organic metal vapor deposition in a nitrogen-containing carrier gas at 500 to 1000°C, to improve light emission output and reduce Vf.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the n-type contact layer is formed by selecting at least one of the method involving increased carrier density and a method involving smaller band gap, then contact resistance is decreased and Vf is lowered, but the layer contains much dislocation and defects which influences the n-side first multi-layered film layer and prevents sufficient improvement of light emission output
Solution Approach 1:
An undoped nitride semiconductor layer is introduced as an intermediary layer between the n-type contact layer (with high carrier density) and the n-side first multi-layered film layer. This intermediary layer acts as a buffer that prevents dislocations and defects from propagating from the contact layer to the multi-layered film layer, while still allowing effective carrier transport to reach the active layer for maintaining low Vf and high light emission output.
Solution Approach 2:
The n-type nitride semiconductor layer is segmented into multiple functional sub-layers: the n-type contact layer for electrical contact, the undoped intermediary layer for defect isolation, and the n-side first multi-layered film layer for light emission enhancement. This segmentation allows each layer to perform its specific function optimally without interfering with the others, resolving the contradiction between maintaining low Vf and preventing defect propagation.
2Reliability
If the n-side first multi-layered film layer is stacked in contact with the n-type contact layer to improve light emission output, then light emission output should be improved, but the layer is undesirably influenced by the dislocation or defects and sufficient effect is not attained
Solution Approach 1:
The undoped nitride semiconductor layer serves as a protective intermediary that shields the n-side first multi-layered film layer from dislocations and defects originating in the n-type contact layer. This ensures high crystallinity quality in the multi-layered film layer, enabling it to achieve its full potential for improving light emission output without being degraded by underlying defects.
3Reliability
If two different types of multi-layered films are grown to lower Vf, then Vf is reduced, but the manufacturing process becomes complicated and manufacturing cost increases
Solution Approach 1:
The invention merges the functions of multiple layers into a single integrated n-type nitride semiconductor layer structure that performs both voltage reduction and defect isolation functions. By combining the n-type contact layer, undoped intermediary layer, and n-side first multi-layered film layer into one continuous n-type region, the design achieves low Vf without requiring separate multi-layered film structures, thereby simplifying the manufacturing process and reducing complexity.
4Reliability
If stacking of a nitride semiconductor layer containing In on the n-side of the active layer is performed, then Vf is lowered, but dislocation and defects of In are induced which affects crystallinity of the active layer and possibly causes decrease in light emission output
Solution Approach 1:
The undoped nitride semiconductor layer acts as a protective barrier between any In-containing layers and the active layer. This intermediary prevents the propagation of In-related dislocations and defects to the active layer, preserving the crystallinity quality of the active layer while still allowing the In-containing layers to contribute to voltage reduction through their band structure properties.
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 solution effectively enhances light emission output and maintains low forward voltage, improving the efficiency and reducing manufacturing complexity and costs, making it suitable for LEDs and laser diodes.
Implementation Method 1
the multi-layered nitride semiconductor layer is grown by organic metal vapor deposition in a carrier gas containing nitrogen at a growth temperature of 500 to 1000° C.
Data Source
AI summary
An object is to provide a nitride semiconductor light emitting device capable of attaining high light emission output while lowering Vf, as well as to provide a manufacturing method thereof. The invention relates to a nitride semiconductor light emitting device, including at least an n-type nitride semiconductor, a p-type nitride semiconductor and an active layer formed between said n-type nitride semiconductor and said p-type nitride semiconductor, wherein the n-type nitride semiconductor includes a multi-layered nitride semiconductor layer having at least twice repeated stacked structure consisting of a first nitride semiconductor layer and a second nitride semiconductor layer, the multi-layered nitride semiconductor layer is formed in contact with the active layer, the first nitride semiconductor layer is a layer containing an n-type impurity, and the second nitride semiconductor layer is an undoped layer or a layer containing said n-type impurity to a concentration lower than said first nitride semiconductor layer.