Face-Up UVC LED Comb Electrodes for Higher Output and Lower Voltage
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Solution Overview
Problem
Face-up type UVC-LEDs have not been put to practical use due to low light output and high forward voltage.
Innovation Solution
A face-up type light emitting element using a group III nitride semiconductor with an emission wavelength of 210 nm to 300 nm, featuring a comb-shaped n-side and p-side electrode structure, where the distance between the p-side and n-side extending portions is 140 μm or less, improving current diffusion and reducing forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a face-up type UVC-LED is used, then light extraction is simplified, but light output is low and forward voltage is high
Solution Approach 1:
The electrodes are divided into multiple comb-shaped extending portions instead of single large electrodes. This segmentation increases the number of current injection points and improves current distribution across the active layer, thereby increasing light output while maintaining the face-up structure's manufacturing simplicity
Solution Approach 2:
The distance between adjacent extending portions of opposite polarity electrodes is optimized to 140 μm or less. This parameter change enhances current diffusion efficiency and reduces forward voltage while maintaining adequate light extraction performance
2Reliability
If electrode spacing is reduced to improve current diffusion, then forward voltage decreases, but light extraction may be affected
Solution Approach 1:
The comb-shaped electrode structure segments the current path into multiple parallel channels through extending portions. This allows reduced spacing between electrodes (improving current diffusion and reducing forward voltage) while the segmented design prevents excessive shadowing of the light extraction path
Solution Approach 2:
The electrode design extends in one dimension (comb teeth extending across the substrate) rather than using simple point contacts. This dimensional extension allows adequate spacing for light extraction in one direction while achieving close spacing for current diffusion in the perpendicular direction
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 described configuration enhances light output and reduces forward voltage, making the face-up type UVC-LED more viable for practical applications.
Implementation Method 1
a light emitting element of a face-up type using a group III nitride semiconductor and having an emission wavelength of 210 nm to 300 nm
Data Source
AI summary
A light emitting element of a face-up type using a group III nitride semiconductor emits light with wavelengths of 210 to 300 nm. The light emitting element has an n-type layer, an active layer provided on the n-type layer, a p-type layer provided on the active layer, an n-side electrode provided on the n-type layer and having a comb shape, a p-side contact electrode provided on and in contact with the p-type layer and transmitting light of the wavelength, and a p-side electrode provided on the p-side contact electrode and having a comb shape. The p-side electrode has p-side extending portions extending in a direction. The n-side electrode has n-side extending portions extending in the direction, each n-side extending portion being disposed between the p-side extending portions adjacent to the n-side extending portion. A distance between the p-side extending portion and the n-side extending portion is 140 μm or less.