Enhancing Light Emission Efficiency in Group III Nitride LEDs
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Summary
Problems
Group III nitride semiconductor light-emitting devices face challenges in achieving high external quantum efficiency due to electric current concentration and light absorption in the electrode, leading to reduced light emission efficiency and luminance, particularly near the bonding pad electrodes.
Innovation solutions
The solution involves forming a light-emitting device with a lower sheet resistance n-type semiconductor layer compared to the light-transmitting electrode, incorporating an insulation layer under the p-type semiconductor layer, and using a light-transmitting electrode with a rough surface to enhance light extraction efficiency and electric characteristics.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a light-transmitting electrode is used to extract light from the p-type semiconductor side, then light extraction efficiency is improved, but electric current concentration occurs directly below the electrode leading to reduced light emission efficiency
Why choose this principle:
The patent applies local quality by creating different sheet resistance regions within the light-transmitting electrode. The electrode has a first region with higher sheet resistance and a second region with lower sheet resistance, allowing different areas to perform different functions: one optimized for light extraction and the other for current distribution, thereby resolving the contradiction between light extraction efficiency and light emission efficiency
Principle concept:
If a light-transmitting electrode is used to extract light from the p-type semiconductor side, then light extraction efficiency is improved, but electric current concentration occurs directly below the electrode leading to reduced light emission efficiency
Why choose this principle:
The patent changes the electrical parameter (sheet resistance) of the light-transmitting electrode by forming it as a multi-layer structure with different materials or thicknesses in different regions. This parameter change allows the electrode to simultaneously achieve both high light extraction efficiency in one region and proper current distribution in another region, resolving the technical contradiction
Application Domain
Data Source
AI summary:
The solution involves forming a light-emitting device with a lower sheet resistance n-type semiconductor layer compared to the light-transmitting electrode, incorporating an insulation layer under the p-type semiconductor layer, and using a light-transmitting electrode with a rough surface to enhance light extraction efficiency and electric characteristics.
Abstract
Disclosed is a group III nitride semiconductor light-emitting device which suppresses electric current concentration in a light-transmitting electrode and a semiconductor layer directly below an electrode to enhance light emission efficiency, suppresses light absorption in the electrode or light loss due to multiple reflection therein to enhance light extraction efficiency, and has superior external quantum efficiency and electric characteristics. A semiconductor layer ( 20 ), in which an n-type semiconductor layer ( 4 ), a light-emitting layer ( 5 ) and a p-type semiconductor layer ( 6 ) are sequentially layered, is formed on a single-crystal underlayer ( 3 ) which is formed on a substrate ( 11 ). A light-transmitting electrode ( 7 ) is formed on the p-type semiconductor layer ( 6 ). An insulation layer ( 15 ) is formed on at least a part of the p-type semiconductor layer ( 6 ), and the light-transmitting electrode ( 7 ) is formed to cover the insulation layer ( 15 ). A positive electrode bonding pad ( 8 ) is provided in a position A corresponding to the insulation layer ( 15 ) provided on the p-type semiconductor layer ( 6 ), on a surface ( 7 a ) of the light-transmitting electrode ( 7 ). A sheet resistance of the n-type semiconductor layer ( 4 ) is lower than a sheet resistance of the light-transmitting electrode ( 7 ).