AlGaN UV LED Clad Layer Wavelength Filtering
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Solution Overview
Problem
Existing semiconductor light-emitting elements struggle to emit ultraviolet light within the 300-360 nm range suitable for ultraviolet treatment while minimizing the emission of wavelengths shorter than 300 nm, which can be harmful.
Innovation Solution
A semiconductor light-emitting element is designed with an n-type AlGaN-based clad layer having a transmittance of 10% or lower for wavelengths shorter than 300 nm and a peak transmittance of 70% or higher for wavelengths between 300-360 nm, utilizing a quantum well structure with specific AlN molar fractions in the active and clad layers to achieve this emission range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an AlGaN-based light-emitting element is designed to emit deep ultraviolet light with wavelength of 300 nm or shorter, then the emission wavelength is reduced to 300 nm or shorter, but harmful ultraviolet light with wavelength shorter than 300 nm is also emitted
Solution Approach 1:
The patent segments the light-emitting structure into multiple functional layers: an active layer that generates broadband deep ultraviolet light, and an n-type clad layer that selectively filters harmful wavelengths. This segmentation allows the system to simultaneously achieve broad emission coverage and harmful wavelength attenuation without requiring separate filtering components.
Solution Approach 2:
The n-type clad layer acts as an intermediary component between the active layer and the external environment. It selectively transmits beneficial ultraviolet light (300 nm and longer) while absorbing harmful shorter wavelength components, thereby mediating the interaction between the light source and treated objects without requiring additional external filters.
2Object-affected harmful factors
If an n-type clad layer with high AlN molar fraction is used to attenuate harmful ultraviolet light, then transmittance for wavelengths shorter than 300 nm is reduced, but transmittance for therapeutic wavelengths (300-360 nm) must be maintained
Solution Approach 1:
The patent optimizes the AlN molar fraction parameter of the n-type clad layer to fall within the range of 0.3 to 0.6. This specific parameter range creates an optimal balance where the clad layer sufficiently attenuates harmful ultraviolet light below 300 nm while maintaining adequate transmittance for therapeutic wavelengths between 300-360 nm, resolving the contradiction between filtering performance and therapeutic light transmission.
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 solution enables the output of ultraviolet light suitable for therapeutic applications while attenuating harmful shorter wavelengths, eliminating the need for additional filters and ensuring safety in ultraviolet treatment.
Implementation Method 1
The n-type clad layer is configured such that a transmittance for ultraviolet light having a wavelength of 300 nm or shorter is 10% or lower
Implementation Method 2
an active layer of an AlGaN-based semiconductor material provided on the n-type clad layer and configured to emit deep ultraviolet light
Data Source
AI summary
A semiconductor light-emitting element includes: an n-type clad layer of an n-type aluminum gallium nitride (AlGaN)-based semiconductor material provided on a substrate; an active layer of an AlGaN-based semiconductor material provided on the n-type clad layer and configured to emit deep ultraviolet light having a wavelength of not shorter than 300 nm and not longer than 360 nm; and a p-type semiconductor layer provided on the active layer. The n-type clad layer is configured such that a transmittance for deep ultraviolet light having a wavelength of 300 nm or shorter is 10% or lower.