Vertical Electrode Light Emitting Device Current Distribution
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Solution Overview
Problem
Conventional light emitting devices using III-V nitride semiconductors face challenges in achieving efficient light emission and current distribution due to limitations in electrode structures, leading to suboptimal quantum efficiency and light extraction.
Innovation Solution
A light emitting device with a novel electrode structure featuring a growth substrate and a vertical type electrode configuration, where the first electrode extends from the second upper surface of the first conductive type semiconductor layer to the lower surface of the substrate, and a second electrode is formed on the second conductive type semiconductor layer, with a current spreading layer to improve current distribution and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional electrode structure is used in light emitting devices, then the device structure is simple, but the internal and external quantum efficiency is insufficient due to non-uniform current distribution and poor light extraction
Solution Approach 1:
The patent transitions from a planar electrode structure to a vertical three-dimensional electrode configuration. The first electrode extends vertically through the substrate from the lower surface to contact the first conductive type semiconductor layer, while the second electrode is positioned on the second conductive type semiconductor layer. This vertical arrangement creates multiple current injection paths and improves current distribution uniformity, thereby enhancing internal quantum efficiency without significantly increasing overall device complexity.
Solution Approach 2:
The electrode system is segmented into distinct functional components: a first electrode with vertical extension through the substrate for current injection, a second electrode on the opposite side for current collection, and a current spreading layer for uniform current distribution. This segmentation allows each component to be optimized independently for its specific function, improving overall device performance while maintaining manageable structural complexity.
2Reliability
If the first electrode extends vertically through the substrate to the first conductive type semiconductor layer, then uniform current flow is achieved, but the device structure becomes more complex
Solution Approach 1:
A current spreading layer is introduced as an intermediary component between the first electrode and the first conductive type semiconductor layer. This current spreading layer receives current from the vertically extending first electrode and distributes it uniformly across the semiconductor layer interface. The intermediary structure effectively decouples the vertical current injection function from the lateral current distribution function, achieving uniform current flow while managing structural complexity through functional specialization.
3Productivity
If a vertical type electrode structure is implemented, then light extraction is improved, but the manufacturing process becomes more difficult
Solution Approach 1:
The first electrode is formed to extend vertically through the substrate during the initial device fabrication process, before final packaging and assembly. This preliminary formation of the vertical electrode structure eliminates the need for subsequent complex through-substrate via formation and electrode bonding steps. By performing the vertical electrode formation early in the manufacturing process, the patent simplifies overall fabrication while maintaining the light extraction benefits of the vertical configuration.
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 proposed design enhances internal and external quantum efficiency by ensuring uniform current flow and improved light extraction, leading to more efficient light emission and better performance in light emitting devices.
Implementation Method 1
a light emitting structure layer including a first conductive type semiconductor layer formed on the substrate and having first and second upper surfaces, in which the second upper surface is closer to the substrate than the first upper surface, an active layer on the first conductive type semiconductor layer, and a second conductive type semiconductor layer on the active layer
Data Source
AI summary
Disclosed are a light emitting device, a light emitting device package, and an illumination system. The light emitting device includes a substrate; a light emitting structure layer including a first conductive type semiconductor layer formed on the substrate and having first and second upper surfaces, in which the second upper surface is closer to the substrate than the first upper surface, an active layer on the first conductive type semiconductor layer, and a second conductive type semiconductor layer on the active layer; a second electrode on the second conductive type semiconductor layer; and at least one first electrode extending at least from the second upper surface of the first conductive type semiconductor layer to a lower surface of the substrate by passing through the substrate.