Nitride Semiconductor Structure With Discontinuous Defect Blocking Layer
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Solution Overview
Problem
Nitride semiconductor structures on silicon substrates face low production yields due to coefficient of thermal expansion (CTE) mismatch and lattice mismatch, leading to defects, electric leakage, and reduced illuminating efficiency, with conventional defect blocking layers offering limited defect reduction and causing stress that can result in cracking.
Innovation Solution
A nitride semiconductor structure incorporating a silicon substrate, a nucleation layer, a discontinuous defect blocking layer, and a buffer layer, where the discontinuous defect blocking layer is grown on the nucleation layer to significantly reduce defect density and stress, allowing for coalescence of the nitride semiconductor layer without voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional defect blocking layer is formed on the buffer layer, then some defects are blocked and stress is released, but the defect density remains high because most defects are formed at the interface between the silicon substrate and the nucleation layer, and the layer structure becomes complex
Solution Approach 1:
The defect blocking layer is divided into a first defect blocking layer formed at the interface between the silicon substrate and the nucleation layer, and a second defect blocking layer formed on the buffer layer. This segmentation allows defects to be blocked at their source interface while maintaining the benefits of the buffer layer, effectively reducing defect density without excessive structural complexity.
Solution Approach 2:
The first defect blocking layer is formed preliminarily at the interface between the silicon substrate and the nucleation layer before the buffer layer is deposited. This preliminary action prevents defects from propagating into the subsequent layers, addressing the root cause of high defect density before the buffer layer is formed.
2Illumination intensity
If the nitride semiconductor layer is grown to sufficient thickness to achieve coalescence, then the illuminating efficiency improves, but the stress accumulated in the layer causes the structure to crack easily
Solution Approach 1:
The defect blocking layers are formed preliminarily to prevent defect propagation and reduce stress accumulation before the nitride semiconductor layer is grown to full thickness. This allows the layer to achieve sufficient thickness for coalescence and high illuminating efficiency without the stress that would otherwise cause cracking.
Solution Approach 2:
The defect blocking layers act as intermediary structures that mediate between the silicon substrate and the nitride semiconductor layer, reducing the stress transmission and allowing the nitride layer to grow to sufficient thickness without cracking.
3Object-generated harmful factors
If a nucleation layer is grown on the silicon substrate to prevent gallium-silicon reactions, then element reaction is prevented, but a large lattice mismatch generates many defects at the interface
Solution Approach 1:
The first defect blocking layer is introduced as an intermediary between the silicon substrate and the nucleation layer. This intermediary layer prevents direct gallium-silicon reactions while having a lattice structure that reduces the mismatch effect, thereby preventing both harmful compound formation and interface defect generation.
Solution Approach 2:
The interface structure is designed as a composite of multiple layers (first defect blocking layer, nucleation layer, buffer layer) with different material properties. This composite structure combines the benefits of preventing gallium-silicon reactions while minimizing lattice mismatch effects through the specific arrangement and properties of each layer.
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 proposed structure effectively decreases defect density and stress, enabling the nitride semiconductor layer to achieve coalescence and improving the quality and luminosity of light emitting diodes by blocking defects and reducing the probability of cracking.
Implementation Method 1
a discontinuous defect blocking layer is grown on the nucleation layer to significantly reduce defect density
Implementation Method 2
the buffer layer is disposed on the discontinuous defect blocking layer and a portion area of the nucleation layer that is not covered by the discontinuous defect blocking layer. The nitride semiconductor layer is disposed on the buffer layer
Implementation Method 3
the discontinuous defect blocking layer is grown on the nucleation layer to significantly reduce defect density and stress, allowing for coalescence of the nitride semiconductor layer without voids
Data Source
AI summary
A nitride semiconductor structure including a silicon substrate, a nucleation layer, a discontinuous defect blocking layer, a buffer layer and a nitride semiconductor layer is provided. The nucleation layer disposed on the silicon substrate, wherein the nucleation layer has a defect density d1. A portion of the nucleation layer is covered by the discontinuous defect blocking layer. The buffer layer is disposed on the discontinuous defect blocking layer and a portion of the nucleation layer that is not covered by the discontinuous defect blocking layer. The nitride semiconductor layer is disposed on the buffer layer. A ratio of a defect density d2 of the nitride semiconductor layer to the defect density d1 of the nucleation layer is less than or equal to about 0.5, at a location where about 1 micrometer above the interface between the nitride semiconductor layer and the buffer layer.