Flip-Chip LED Current Blocking Layout for Thermal Degradation
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Solution Overview
Problem
Light emitting devices, particularly those using Group III-V nitride semiconductors in flip-chip configuration, face thermal degradation issues due to high driving voltage, especially when emitting deep ultraviolet light, as the path for carrier supply and heat radiation is the same, leading to increased heat loss rates and reduced reliability.
Innovation Solution
Incorporation of a current blocking layer in the ohmic layer to prevent thermal degradation by blocking current injection in the maximum heating area, thereby improving heat loss rates and extending the device's lifetime even at high driving voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a flip-chip configuration is used to improve heat radiation, then heat dissipation is enhanced, but thermal degradation occurs because the carrier supply path and heat radiation path are the same
Solution Approach 1:
The patent segments the ohmic layer into multiple regions with different functions: a first region for carrier injection and a second region for heat radiation. This spatial segmentation allows independent optimization of carrier supply and heat dissipation paths, resolving the contradiction by preventing thermal degradation in the carrier injection region while maintaining effective heat radiation through the dedicated radiation region.
Solution Approach 2:
The patent applies local quality by creating regions with different electrical properties within the ohmic layer. The first region has properties optimized for carrier injection while the second region has properties optimized for heat radiation. This local differentiation allows each region to perform its specific function effectively, solving the contradiction between heat dissipation and thermal degradation.
2Illumination intensity
If deep ultraviolet light is emitted to achieve high performance, then light output is improved, but heat loss rate increases due to high driving voltage
Solution Approach 1:
The patent extracts the heat radiation function from the carrier injection path by creating a dedicated second region in the ohmic layer that is specifically designed for heat radiation. This separation allows the device to maintain high driving voltage for deep ultraviolet light emission while providing an independent pathway for heat dissipation, thereby reducing the overall heat loss rate.
3Ease of manufacture
If the ohmic layer structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but current crowding and thermal degradation occur
Solution Approach 1:
The patent segments the ohmic layer into functionally distinct regions that can be formed using standard semiconductor manufacturing techniques. This segmentation prevents current crowding and thermal degradation while maintaining compatibility with existing manufacturing processes, thus resolving the contradiction between manufacturing simplicity and device reliability.
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 current blocking layer effectively reduces thermal degradation, stabilizes forward voltage variations over time, and enhances the reliability and longevity of light emitting devices, especially those emitting deep ultraviolet light.
Implementation Method 1
a current blocking layer disposed in an ohmic layer
Implementation Method 2
A light emitting diode (LED) is a kind of semiconductor that converts electricity into infrared light or light used for receiving or transmitting signals
Data Source
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AI summary
A light emitting device according to embodiments includes a substrate, a light emitting structure disposed under the substrate and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, a submount disposed to face the substrate, first and second metal pads disposed on the submount to be spaced apart from each other, a first bump disposed on the first metal pad, a plurality of second bumps disposed on the second metal pad to be spaced apart from each other, a first ohmic layer interposed between the first conductive semiconductor layer and the first bump, a second ohmic layer interposed between the second conductive semiconductor layer and the plurality of second bumps, a first spreading layer interposed between the first ohmic layer and the first bump, a second spreading layer interposed between the second ohmic layer and the plurality of second bumps, and a current blocking layer disposed in a maximum heating area of the second ohmic layer overlapping an area between the plurality of second bumps in a thickness direction of the light emitting structure such that the current blocking layer does not cut the second ohmic layer in a horizontal direction intersecting the thickness direction.