GaN Schottky Diode Segmented Metallization for Low On-State Resistance
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Solution Overview
Problem
GaN Schottky diodes with long and narrow teeth exhibit significant resistance in the on state, limiting their efficiency in high-voltage and high-power applications.
Innovation Solution
The diode structure is modified to include a silicon oxide layer between the silicon support and undoped silicon, with doped silicon areas in contact with vias that extend to the support, and a honeycomb or checkerboard pattern of metallizations to reduce resistance, using vias to connect metallizations and minimize surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the teeth of the combs are long and narrow, then the voltage withstand capability is improved, but the on-state resistance increases significantly
Solution Approach 1:
The diode structure is divided into multiple unit cells arranged in a periodic pattern, with each unit cell containing Schottky metallization regions and ohmic metallization regions separated by isolation regions. This segmentation allows the voltage withstand capability to be distributed across multiple junctions while reducing the resistance through parallel current paths
Solution Approach 2:
Different regions of the diode are assigned different functionalities: Schottky metallization regions are optimized for voltage blocking with appropriate doping levels, while ohmic metallization regions are optimized for low resistance contact with higher doping levels. The isolation regions provide electrical separation between adjacent unit cells, enabling each region to perform its specific function optimally
2Strength
If the GaN layer is made thicker to improve voltage withstand capability, then the voltage blocking performance is improved, but the layer becomes more brittle and difficult to manufacture
Solution Approach 1:
The doping level of the GaN layer is varied spatially to optimize both voltage blocking and mechanical properties. The Schottky-contacted regions are doped at a first level (1e16 to 1e18 atoms/cm³) for voltage blocking, while the ohmic-contacted regions are doped at a second level (1e18 to 1e20 atoms/cm³) for low resistance contact and improved mechanical flexibility. This parameter change allows the GaN layer to achieve the required voltage withstand capability while maintaining manufacturability
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
This configuration reduces on-state resistance, minimizes surface area, and lowers costs by allowing thicker GaN layers without brittleness issues, while maintaining high voltage withstand capabilities.
Implementation Method 1
a layer of silicon oxide between the doped silicon support and the undoped silicon layer
Implementation Method 2
The first metallization forms a Schottky contact with the AlGaN layer
Implementation Method 3
areas of doped silicon in contact with the second vias
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
Schottky diode comprising, between a lower face and an upper face: a silicon support (31); an undoped GaN layer (5); one or more motifs formed in an AlGaN layer (7) each of which extends between a first metallization (37) forming an ohmic contact and a second metallization (40) forming a Schottky contact; first vias (46) extending from the second metallizations towards the upper face; and second vias (38) extending from the first metallizations towards the lower face.