Concentric Coplanar Diodes for GaN Current Injection
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Solution Overview
Problem
Semiconductor diodes, particularly gallium nitride light-emitting diodes, face challenges in efficiently injecting electrical supply current due to high resistivity in N-type doped gallium nitride cathode regions, leading to high series resistance and potential differences between diodes, which complicates insulation and reduces luminous efficiency.
Innovation Solution
The implementation of concentric coplanar diodes with continuous active regions separated by annular trenches, where metallization connects diodes over the entire trench length, and biased electrodes with polygonal ring patterns for improved current distribution and injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional diode arrangements with limited contact regions are used, then device structure is simpler, but series resistance is high and current injection is inefficient
Solution Approach 1:
The patent transitions from planar contact regions to three-dimensional annular trenches that extend vertically through the semiconductor stack. This dimensional change allows metallization to contact the cathode layer along the entire trench length, dramatically increasing the effective contact area and reducing series resistance without expanding the device footprint.
Solution Approach 2:
The annular trenches are positioned concentrically around the active region, with metallization nested within the trench structure. This nesting approach allows the interconnection metallization to be integrated within the diode structure itself, providing extensive contact length while maintaining a compact overall form factor.
2Reliability
If diodes are arranged with extended contact regions to reduce resistance, then series resistance decreases, but insulation between adjacent diodes becomes more difficult
Solution Approach 1:
The patent divides the semiconductor structure into discrete diode units separated by annular trenches. Each diode's active region is isolated from its neighbors by these trenches, which are filled with metallization for interconnection. This segmentation allows extended effective contact area while maintaining electrical isolation between adjacent diodes through the trench structure.
Solution Approach 2:
The annular trenches act as intermediary structures between adjacent diodes. By filling the trenches with metallization and positioning them concentrically around each active region, the patent creates a mediating structure that provides both electrical connection and physical separation, resolving the conflict between reducing resistance and maintaining insulation.
3Reliability
If conventional metallization connections are used, then manufacturing is simpler, but contact length is limited and series resistance remains high
Solution Approach 1:
The annular trenches are formed and metallization is deposited in advance, creating pre-configured interconnection structures before final device assembly. This preliminary preparation of the trench metallization allows for optimized current distribution and reduced series resistance while maintaining manufacturing efficiency through standardized process integration.
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 significantly reduces series resistance and potential differences between diodes, enhancing current injection and luminous efficiency while relaxing insulation constraints.
Implementation Method 1
an interconnection metallization (521i) is provided, connecting the cathode contact metallization (109) of the diode Di to the anode contact metallization (111) of diode Di+1
Implementation Method 2
the length of the contact regions between two consecutive diodes of the series association of diodes D1, D2, ..., Dn is limited to the length of an edge of the active region of a diode. Since the connection resistance is inversely proportional to the length of the interconnected contact regions, it follows that the overall series resistance of the device is relatively high.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5B
AI summary
The invention relates to a device comprising a plurality of interconnected concentric coplanar diodes (D1, D2, D3, D4).