UV AlInGaN LED Reflective Structure for TM Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The low light extraction efficiency of ultraviolet light-emitting diodes (UV LEDs) based on AlInGaN material, particularly in the transverse magnetic (TM) mode, limits their sterilization efficiency and usage scenarios due to significant light absorption within the material.
Innovation Solution
A method involving the growth of an epitaxial structure with an inverted-trapezoid metal layer of high reflectivity for ultraviolet light, which reflects and extracts TM mode light, improving the extraction efficiency by preventing continuous propagation and absorption within the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the Al content of the AlInGaN quantum well layer is increased to reduce wavelength, then the light extraction mode shifts from TE to TM, but the TM mode light is absorbed inside the material resulting in decreased light extraction efficiency
Solution Approach 1:
An inverted-trapezoid metal layer with high reflectivity for ultraviolet light is introduced as an intermediary component. This metal layer reflects TM mode light that would otherwise be absorbed within the material back toward the quantum well layer, enabling efficient extraction of ultraviolet light while maintaining the desired wavelength reduction through high Al content in the quantum well layer.
2Temperature
If the Al content of the AlInGaN quantum well layer is increased, then the wavelength is reduced for deeper ultraviolet emission, but the TM mode light absorption increases dramatically
Solution Approach 1:
The inverted-trapezoid metal layer serves as a mediator that enables the use of high Al content in the quantum well layer (for deeper UV emission) while compensating for the increased TM mode light absorption through its high reflectivity, thus maintaining efficient light extraction at shorter wavelengths.
3Ease of manufacture
If conventional AlInGaN light-emitting diode structure is used, then the device is simple to manufacture, but the light extraction efficiency is low resulting in low luminous brightness
Solution Approach 1:
The patent introduces an inverted-trapezoid metal layer that extends in the vertical dimension (thickness) and lateral dimension (width variation). This three-dimensional structure increases the reflective path length and improves TM mode light extraction without significantly complicating the manufacturing process, thereby enhancing luminous brightness while maintaining ease of manufacture.
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 approach significantly enhances the TM mode light extraction efficiency of UV LEDs, leading to improved brightness and sterilization capabilities, making them more suitable for various applications.
Implementation Method 1
reflecting and extracting ultraviolet light emitted from an AlInGaN quantum well by using an inverted-trapezoid metal layer with high reflectivity for ultraviolet light
Data Source
AI summary
Disclosed is a method for improving transverse magnetic (TM) mode light extraction efficiency of an ultraviolet AlInGaN light-emitting diode. As the Al content in the AlInGaN light-emitting diode increases, the wavelength decreases gradually. Meanwhile, light extraction dominated by a TE mode is switched to light extraction dominated by a TM mode. To improve the light extraction efficiency of the TM mode, in the present disclosure, a passivation layer is first grown in an etched N-type electrode region and an edge electrode region, and then a reflective metal region of an inverted trapezoidal structure is etched in the region of the passivation layer. Metal with high reflectivity for ultraviolet light is evaporated in the region of the inverted trapezoidal structure, and TM light generated in a quantum well can be reflected to the external through a metal layer with high reflectivity, which improves the TM mode light extraction efficiency.