GaN LED Electrode Extensions for Current Spreading
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Solution Overview
Problem
The formation of electrode extensions in GaN-based light emitting diodes reduces the light emitting area due to the space required for their formation, which also affects current spreading efficiency.
Innovation Solution
The design includes lower and upper electrode extensions with specific geometries that extend from the electrode pads, allowing for improved current spreading while minimizing the area occupied by these extensions, thus maintaining a larger light emitting area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode extensions are formed to improve current spreading, then current spreading capability is improved, but light emitting area is reduced
Solution Approach 1:
The patent transitions from two-dimensional planar extensions to three-dimensional vertical extensions. The electrode extensions extend vertically from the electrode pads toward the opposing electrode, utilizing the vertical dimension to achieve current spreading without consuming lateral light emitting area. This dimensional change allows current to spread through the vertical path while maintaining a compact lateral footprint.
Solution Approach 2:
The electrode extension structure is segmented into multiple parts: a first electrode extension extending from the first electrode pad, and a second electrode extension extending from the second electrode pad. These segmented extensions work together to provide comprehensive current spreading coverage without requiring a single large continuous extension that would consume excessive light emitting area.
2Reliability
If extensions enclose opposing extensions to improve current spreading, then current spreading is enhanced, but light emitting area is further reduced
Solution Approach 1:
The enclosing structure utilizes the vertical dimension rather than lateral expansion. The first and second electrode extensions extend vertically to enclose the opposing extensions in the vertical space above the light emitting area, rather than extending laterally to enclose them in the horizontal plane. This preserves the lateral light emitting area while achieving the enclosing configuration for enhanced current spreading.
3Reliability
If space is allocated for electrode extensions, then current spreading capability is improved, but forward voltage increases
Solution Approach 1:
By utilizing the vertical dimension for extension growth, the lateral footprint of extensions is minimized. This allows more of the lateral area to remain as active light emitting region, maintaining higher current density and reducing forward voltage while still achieving effective current spreading through the vertical extension structure.
Solution Approach 2:
The patent optimizes the extension length parameter - extending vertically to a controlled distance that provides sufficient current spreading capability without过度 occupying space. This parameter optimization balances current spreading effectiveness with maintaining adequate light emitting area and current density to keep forward voltage low.
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 results in a 5% increase in light emitting area, a 2.35% increase in light output, and a 1.89% reduction in forward voltage, enhancing both light emission and power efficiency.
Implementation Method 1
The electrode pads of the LED are electrically connected to an external power supply, which drives the LED
Implementation Method 2
Gallium nitride (GaN)-based light emitting diodes (LEDs) have been used for various applications
Implementation Method 3
GaN-based LED is generally formed by growing epitaxial layers on a sapphire substrate
Data Source
AI summary
An exemplary embodiment of the present invention discloses a light emitting diode including a lower contact layer having a first edge, a second edge opposite to the first edge, a third edge connecting the first edge to the second edge, and a fourth edge opposite to the third edge, a mesa structure arranged on the lower contact layer, the mesa structure including an active layer and an upper contact layer, a first electrode pad arranged on the lower contact layer, a second electrode pad arranged on the mesa structure, a first lower extension and a second lower extension extending from the first electrode pad towards the second edge, distal ends of the first lower extension and the second lower extension being farther away from each other than front ends thereof contacting the first electrode pad, and a first upper extension, a second upper extension, and a third upper extension extending from the second electrode pad. In addition, the first upper extension and the second upper extension extend from the second electrode pad to enclose the first lower extension and the second lower extension, and the third upper extension extends to a region between the first lower extension and the second lower extension.