Nitride Semiconductor Light-Emitting Device with Hydrogen-Storage Alloy Tunnel Junction
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Solution Overview
Problem
Conventional nitride semiconductor light-emitting diodes face limitations in light extraction efficiency due to high contact resistance and insufficient light transmission from electrodes, particularly when using ITO films, which degrade under high temperatures and current densities.
Innovation Solution
A nitride semiconductor light-emitting device structure is developed with a metal layer made of a hydrogen-storage alloy between the p-type and n-type nitride semiconductor layers, forming a tunnel junction to enhance contact area and carrier diffusion, and optionally incorporating semiconductor layers doped with both n-type and p-type dopants to improve crystallinity and reduce driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO transparent conductive film is used as electrode on p-type nitride semiconductor layer, then light transmittance and current diffusion are improved, but contact resistance increases and device reliability deteriorates under high temperature and current density
Solution Approach 1:
An n-type nitride semiconductor layer is introduced as an intermediary between the p-type nitride semiconductor layer and the electrode. This intermediate layer forms a tunnel junction that enables low-resistance ohmic contact while being positioned to minimize impact on light extraction. The n-type layer acts as a mediator that resolves the conflict between achieving low contact resistance and maintaining device stability under operational conditions.
Solution Approach 2:
The electrode structure is designed as a composite system combining p-type nitride semiconductor layer, n-type nitride semiconductor layer, and transparent conductive film. This composite structure leverages the complementary properties of each layer: the p-type layer provides good light extraction, the n-type layer provides low contact resistance through tunnel junction, and the transparent conductive film provides current diffusion and transmittance.
2Device complexity
If electrode is formed directly on p-type nitride semiconductor layer surface, then device structure is simplified, but light extraction efficiency is insufficient due to high contact resistance
Solution Approach 1:
The n-type nitride semiconductor layer serves as an intermediary component that reconciles the contradiction between structural simplicity and performance. While it adds one layer to the structure, it enables significantly improved light extraction efficiency through the tunnel junction mechanism, achieving a better overall balance between complexity and performance than direct electrode formation.
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 significantly increases light extraction efficiency by improving ohmic contact and reducing driving voltage, while maintaining high quantum efficiency and preventing temperature rise.
Implementation Method 1
the metal layer is preferably made of a hydrogen-storage alloy
Implementation Method 2
forming a tunnel junction to enhance contact area and carrier diffusion
Data Source
AI summary
A nitride semiconductor light-emitting device comprises a substrate, and a first n-type nitride semiconductor layer, an emission layer, a p-type nitride semiconductor layer, a metal layer and a second n-type nitride semiconductor layer stacked on the substrate successively from the side closer to the substrate, with an electrode provided on the surface of the second n-type nitride semiconductor layer or above the surface of the second n-type nitride semiconductor layer. The metal layer is preferably made of a hydrogen-storage alloy.