Far-UVC LED Spacer Composition for Higher Emission Efficiency
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Solution Overview
Problem
Far-UVC light emitting diodes (LEDs) have low external quantum efficiencies due to limitations in increasing the Al composition ratio and modifications in electronic structure at high Al composition ratios, leading to dominant TM emission and electron overflow, which reduces emission efficiency.
Innovation Solution
The implementation of a composition-graded spacer layer and a thinner barrier layer in the ultraviolet light emitting diodes, with the Al composition ratio varying along the thickness direction, enhances electron injection efficiency and suppresses electron overflow, favoring TE emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the Al composition ratio is increased to achieve shorter wavelength emission in Far-UVC range, then the emission wavelength decreases to 210-230 nm, but the external quantum efficiency decreases exponentially to 0.03% or less
Solution Approach 1:
The patent applies local quality by creating a composition-graded spacer layer where the Al composition ratio varies spatially along the thickness direction. The spacer layer has higher Al composition near the emitting layer interface and lower Al composition near the electron blocking layer interface, optimizing electron injection at each interface while maintaining the overall high Al composition needed for Far-UVC emission.
Solution Approach 2:
The patent changes the Al composition ratio parameter continuously through the spacer layer thickness, transitioning from high Al composition (0.85-0.95) near the emitting layer to lower Al composition (0.75-0.85) near the electron blocking layer. This parameter gradient optimizes both electron injection efficiency and electron blocking performance simultaneously.
2Length of moving object
If the Al composition ratio is increased to achieve Far-UVC emission, then the emission wavelength reaches 210-230 nm, but electron overflow increases due to insufficient electron blocking function
Solution Approach 1:
The patent applies local quality by creating a composition-graded spacer layer where the Al composition ratio varies spatially along the thickness direction. The spacer layer has higher Al composition near the emitting layer interface and lower Al composition near the electron blocking layer interface, optimizing electron injection at each interface while maintaining the overall high Al composition needed for Far-UVC emission.
Solution Approach 2:
The composition-graded spacer layer acts as an intermediary between the emitting layer and the electron blocking layer. It provides a gradual transition in Al composition that facilitates controlled electron transport while preventing excessive electron overflow to the electron blocking layer, thereby reducing energy loss.
3Length of moving object
If the Al composition ratio is increased to achieve Far-UVC emission, then the emission wavelength reaches 210-230 nm, but TM emission becomes dominant over TE emission reducing light extraction efficiency
Solution Approach 1:
The patent applies local quality by creating a composition-graded spacer layer where the Al composition ratio varies spatially along the thickness direction. The spacer layer has higher Al composition near the emitting layer interface and lower Al composition near the electron blocking layer interface, optimizing electron injection at each interface while maintaining the overall high Al composition needed for Far-UVC emission.
Solution Approach 2:
The patent changes the Al composition ratio parameter continuously through the spacer layer thickness, transitioning from high Al composition (0.85-0.95) near the emitting layer to lower Al composition (0.75-0.85) near the electron blocking layer. This parameter gradient optimizes both electron injection efficiency and electron blocking performance simultaneously.
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 design significantly improves the emission efficiency of Far-UVC LEDs by increasing internal quantum efficiency and reducing electron overflow, achieving higher light output and improved light extraction.
Implementation Method 1
an ultraviolet light emitting diode having an AlGaN-based crystal or an InAlGaN-based crystal
Data Source
AI summary
To improve the emission efficiency of ultraviolet light emitting diodes in the Far-UVC wavelength range, the ultraviolet light emitting diode in one embodiment has a semiconductor layer that includes aluminum, gallium and nitrogen. It may also include Indium. In various embodiments, it may include an AlGaN-based crystal or an InAlGaN-based crystal. The relative atomic ratios of aluminum, gallium, nitrogen and indium may vary at different positions in the layer. The diode comprises a light emitting layer, a spacer layer and an electron blocking layer in this order along the electron flow direction. The Al composition ratio in the spacer layer varies along the position in the thickness direction of the layers. The ultraviolet light emitting diode of the embodiment of the present disclosure can be provided with the emitting layer comprising at least one barrier layer and at least two quantum well layers sandwiching the barrier layer.