Semiconductor Light Emitting Element Reflecting Layer Design
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Solution Overview
Problem
Semiconductor light emitting elements with reflecting layers under pad electrodes face challenges in achieving high light extraction efficiency due to light absorption and uneven electrical current distribution.
Innovation Solution
A semiconductor light emitting element design featuring a semiconductor multilayer structure with a reflecting layer of smaller area than the transparent electrodes, covered by a transparent insulating material, and positioned under the pad electrode to enhance light reflection and extraction efficiency, while ensuring uniform electrical current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a reflecting layer is formed under the pad electrode to prevent light absorption, then light extraction efficiency is improved, but the pad electrode still absorbs light and forward voltage increases due to uneven current distribution
Solution Approach 1:
A transparent insulating layer is introduced as an intermediary between the reflecting layer and the pad electrode. This mediator prevents direct contact between the conductive pad electrode and the reflecting layer, eliminating the harmful light absorption effect while maintaining the beneficial light reflection effect. The transparent insulating layer allows light to pass through it without significant absorption, thus resolving the contradiction between preventing light absorption and maintaining electrical functionality.
Solution Approach 2:
The structure is segmented into distinct functional layers: the reflecting layer for light reflection, the transparent insulating layer for electrical isolation and light transmission, and the pad electrode for electrical connection. This segmentation allows each layer to perform its specific function without interfering with others, particularly preventing the pad electrode from absorbing light while maintaining the reflecting layer's light extraction enhancement capability.
2Productivity
If a reflecting layer is formed under the pad electrode to enhance light reflection, then light emission output is improved, but electrical current distribution becomes uneven causing increased forward voltage
Solution Approach 1:
The transparent insulating layer serves as a mediator that electrically isolates the pad electrode from the reflecting layer. This isolation prevents the pad electrode from creating localized current concentration points on the reflecting layer, thereby maintaining uniform current distribution across the light emitting layer while still allowing the reflecting layer to enhance light emission output through improved light extraction efficiency.
Solution Approach 2:
The transparent insulating layer is strategically positioned only where needed - between the pad electrode and the reflecting layer - to provide local electrical isolation. This localized application maintains uniform current distribution in critical areas while preserving the overall light reflection functionality of the reflecting layer, thus resolving the contradiction between light emission enhancement and current distribution uniformity.
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 design significantly improves light extraction efficiency and maintains similar forward voltage characteristics compared to conventional elements, with enhanced light emission output and reduced absorption of light by the pad electrode.
Implementation Method 1
a reflecting layer formed on the first transparent electrode, and comprising a smaller area than the first transparent electrode
Data Source
AI summary
A semiconductor light emitting element includes a semiconductor multilayer structure including a first conductive type layer, a second conductive type layer and a light emitting layer sandwiched between the first conductive type layer and the second conductive type layer, a first transparent electrode formed on the second conductive type layer, a reflecting layer formed on the first transparent electrode, and including a smaller area than the first transparent electrode, a second transparent electrode formed on the first transparent electrode so as to cover the reflecting layer, and a pad electrode formed on the second transparent electrode and in a region above the reflecting layer.