Group III-Nitride SOI Structure for Resistivity and RF Loss Control
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Solution Overview
Problem
Group III-nitride-based heterostructures on silicon substrates face issues with resistivity drop and p-type dopant diffusion, leading to capacitive coupling, RF losses, and linearity problems for high-power and high-frequency applications.
Innovation Solution
A semiconductor structure using a Silicon-On-Insulator substrate with a trap-rich layer and n-type doped top layer to confine and compensate for Group III element diffusion, enhancing resistivity and reducing power losses and linearity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Group III-nitride heterostructures are grown on silicon substrates, then manufacturing compatibility is improved, but resistivity drops and p-type dopant diffusion occurs
Solution Approach 1:
An intermediate layer is introduced between the silicon substrate and the Group III-nitride heterostructure. This intermediate layer acts as a mediator that prevents direct interaction between silicon and the nitride layers, thereby blocking the diffusion of Group III elements into the silicon substrate while maintaining manufacturing compatibility. The intermediate layer effectively decouples the substrate from the active heterostructure, solving the resistivity degradation problem.
Solution Approach 2:
The substrate structure is segmented into multiple distinct layers: a silicon base layer, an intermediate layer, and a top layer. This segmentation isolates the silicon substrate from the Group III-nitride heterostructure, preventing harmful dopant diffusion while preserving the benefits of silicon-based manufacturing. The intermediate layer serves as a buffer zone that separates the two material systems.
2Ease of manufacture
If Group III-nitride heterostructures are grown on silicon substrates, then manufacturing compatibility is improved, but power losses increase due to capacitive coupling
Solution Approach 1:
The intermediate layer acts as an electrical isolator that reduces capacitive coupling between the Group III-nitride heterostructure and the silicon substrate. By introducing this intermediary layer, the parasitic capacitance is minimized, thereby reducing power losses in high-frequency applications while maintaining compatibility with silicon-based manufacturing processes.
3Ease of manufacture
If Group III-nitride heterostructures are grown on silicon substrates, then manufacturing compatibility is improved, but linearity problems arise due to harmonic frequencies
Solution Approach 1:
The intermediate layer serves as a buffer that prevents direct electrical interaction between the silicon substrate and the Group III-nitride heterostructure. This isolation reduces the generation of harmonic frequencies and improves the linearity of devices, while still allowing compatibility with existing silicon-based manufacturing infrastructure.
4Device complexity
If conventional silicon substrates are used, then manufacturing simplicity is maintained, but resistivity drops at the interface
Solution Approach 1:
The substrate is divided into three layers: a simple silicon base layer for manufacturing compatibility, an intermediate layer to prevent dopant diffusion, and a top layer for device fabrication. This segmentation maintains the simplicity of silicon-based manufacturing while adding only the necessary intermediate functionality to preserve resistivity.
Solution Approach 2:
An intermediate layer is inserted between the conventional silicon substrate and the Group III-nitride heterostructure. This intermediary layer preserves the high resistivity of silicon by preventing the diffusion of p-type dopants from the nitride layers, while maintaining compatibility with conventional silicon processing techniques.
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 structure achieves improved resistivity, reduced power losses, and better linearity, compatible with existing technologies, suitable for high-power and high-frequency applications.
Implementation Method 1
the diffusion or migration of Group III elements into the silicon substrate
Implementation Method 2
a trap-rich layer; and wherein the intermediate layer comprises: a trap-rich layer
Implementation Method 3
the top layer comprises n-type doped silicon
Implementation Method 4
a two dimensional electron gas, also referred to as 2DEG, is generated by the spontaneous and piezoelectric polarization between the two active layers
Implementation Method 5
spontaneous and piezoelectric polarization between the two active layers
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A semiconductor structure (1) comprising: - a Silicon-On-lnsulator substrate (101) comprising: · a silicon base layer (10); · an intermediate layer (11) on top of said base layer (10) and comprising: · trap-rich layer (111); and · a buried insulator (121) on top of a trap-rich layer (111); and · a n-type doped silicon top layer (12) on top of said intermediate layer (11); and an epitaxial IIl-N semiconductor layer stack (202) on top of said Silicon-On-lnsulator substrate (101), comprising: o a first active lll-N layer (21) on top of said top layer (12); o a second active lll-N layer (22) on top of said first active lll-N layer (21); with a two dimensional Electron Gas (200) between said first active lll-N layer (21) and said second active lll-N layer (22).