GaN MPS Diode Fabrication via Regrown Epitaxial Layers
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Solution Overview
Problem
Current power electronics systems lack efficient high-voltage switches with low capacitance and very low leakage current, particularly in reverse bias conditions, limiting their performance in high-voltage applications.
Innovation Solution
The development of merged p-i-n and Schottky (MPS) diodes using gallium nitride (GaN) based epitaxial layers, which incorporate regrown n-type and p-type regions to create a device structure that combines the low turn-on voltage of a Schottky diode with the low reverse leakage current of a p-n diode, leveraging the superior material properties of GaN for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Schottky diode structure is used, then the turn-on voltage is low, but the reverse leakage current is high
Solution Approach 1:
The patent merges a Schottky diode and a p-n diode into a single merged p-n Schottky (MPS) diode structure. The Schottky contact provides low turn-on voltage in forward bias, while embedded p-n junctions provide low reverse leakage current through depletion region formation. This combination allows the device to exhibit both low turn-on voltage and low reverse leakage current simultaneously, resolving the technical contradiction between these two parameters.
2Object-generated harmful factors
If a p-n diode structure is used, then the reverse leakage current is low, but the turn-on voltage is high
Solution Approach 1:
The MPS diode structure combines Schottky and p-n diode functionalities. The Schottky contact region provides low turn-on voltage (0.6-0.8V) in forward bias operation, while the embedded p-n junctions provide low reverse leakage current through their depletion regions. This merging allows the device to overcome the high turn-on voltage limitation of conventional p-n diodes while maintaining low reverse leakage current.
3Ease of manufacture
If conventional Si or SiC material systems are used, then manufacturing isๆ็, but performance in high-voltage applications is limited
Solution Approach 1:
The patent transitions from conventional Si or SiC material systems to GaN-based semiconductor materials. GaN offers superior material properties including higher breakdown electric field strength, higher electron mobility, and higher thermal conductivity. These parameter changes enable the MPS diode to achieve excellent high-voltage blocking capability and fast switching performance while maintaining manufacturing feasibility through epitaxial growth 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 MPS diodes exhibit lower leakage currents for large reverse voltages with minimal penalty in forward turn-on voltage, offering a high voltage switch with excellent trade-offs between blocking voltage and forward resistance, suitable for high-voltage applications and retaining fast switching speed and low capacitance.
Implementation Method 1
regrowing a GaN-based epitaxial layer including n-type material in regions overlying portions of the n-type GaN-based epitaxial layer, and p-type material in regions overlying the plurality of dopant sources
Data Source
AI summary
A method for fabricating a merged p-i-n Schottky (MPS) diode in gallium nitride (GaN) based materials includes providing an n-type GaN-based substrate having a first surface and a second surface. The method also includes forming an n-type GaN-based epitaxial layer coupled to the first surface of the n-type GaN-based substrate, and forming a p-type GaN-based epitaxial layer coupled to the n-type GaN-based epitaxial layer. The method further includes removing portions of the p-type GaN-based epitaxial layer to form a plurality of dopant sources, and regrowing a GaN-based epitaxial layer including n-type material in regions overlying portions of the n-type GaN-based epitaxial layer, and p-type material in regions overlying the plurality of dopant sources. The method also includes forming a first metallic structure electrically coupled to the regrown GaN-based epitaxial layer.