Tapered Electrode and Current Block Layer for Uniform Current Distribution
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in achieving uniform current distribution and light emission efficiency due to high current density concentrations, which can lead to electromigration and reduced reliability.
Innovation Solution
The semiconductor light emitting device incorporates a current block layer with reduced conductivity between the semiconductor layers and electrodes, dispersing electron flow and preventing concentration, while the electrode width decreases with distance from the electrode pads to homogenize current density and enhance light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode width is maintained constant across the semiconductor layer, then the electrical connection is simplified, but the current density becomes non-uniform leading to electromigration and reduced reliability
Solution Approach 1:
The electrode width is made variable rather than constant, creating a tapered structure where the width changes along the extension direction. This dynamic geometry allows current density to be redistributed uniformly across the semiconductor layer, preventing electromigration while maintaining electrical functionality.
Solution Approach 2:
Different sections of the electrode have different widths to serve different functions: wider sections near contact points handle higher current input, while narrower sections farther away distribute current more sparsely. This local variation in electrode quality optimizes current distribution throughout the device.
2Reliability
If a current block layer is added to disperse electron flow, then current distribution uniformity improves, but the device structure becomes more complex
Solution Approach 1:
A current block layer is introduced as an intermediary element between the electrode and the semiconductor layer. This intermediate layer actively manages electron flow by blocking direct contact in certain regions, thereby dispersing current distribution and preventing concentration that would lead to electromigration.
3Reliability
If the electrode extends further over the semiconductor layer, then the electrical connection area increases, but light absorption by the electrode increases reducing emission efficiency
Solution Approach 1:
The electrode width varies dynamically along its extension, being wider near the contact region for reliable electrical connection and narrower toward the light emission region to minimize light absorption. This tapered profile balances electrical and optical requirements.
Solution Approach 2:
The electrode has different width characteristics in different regions: wider sections provide robust electrical connection while narrower sections reduce optical interference. This local differentiation allows the single electrode structure to fulfill multiple competing functions.
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 semiconductor light emitting device with improved uniform current distribution and light emission efficiency, reducing the risk of electromigration and increasing reliability by dispersing current density and preventing light absorption by electrodes.
Implementation Method 1
a layer (50) is provided between part of the first semiconductor layer (10) and part of the first electrode (60) and has conductivity less than conductivity of the first electrode (60)
Data Source
Figure 1A~1C
Figure 2~3B
Figure 4A~4C
AI summary
According to one embodiment, a semiconductor light emitting device (1) includes a semiconductor layer (80), an electrode pad (70), a first electrode (60), a second electrode (40) and a layer (50). The semiconductor layer (80) includes a first semiconductor layer (10), a second semiconductor layer (20), and a light emitting layer (30). The electrode pad (70) is provided in adjacent to the semiconductor layer (80). The first electrode (60) is connected to the electrode pad (70) with one end, extends from the electrode pad (70), and is connected to the first semiconductor layer (10). The second electrode (40) is connected to the second semiconductor layer (20). The layer (50) with lower conductivity is provided between part of the first semiconductor layer (10) and part of the first electrode (60). The first electrode (60) has an electrode width. The electrode width is in a direction perpendicular to a direction in which the first electrode (60) extends. The electrode width decreases with distance from the electrode pad (70).