UV LED N-Electrode Area and P-Electrode Dot Pattern
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Solution Overview
Problem
Light-emitting elements that emit UV-B or UV-C wavelengths face efficiency losses and increased forward voltage due to high sheet resistance and contact resistance in the n-type semiconductor layer, limiting light emission to regions close to the n-electrode.
Innovation Solution
A light-emitting element with an n-type semiconductor layer of AlxGa1−xN composition, p-type semiconductor layer, and a light-emitting layer, where the n-electrode covers at least 25% but not more than 50% of the chip area, and p-electrodes are arranged in a dot pattern with specific dimensions and shapes to optimize light emission and reduce inactive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the n-type semiconductor layer uses high Al composition (x≥0.65) for UV-B or UV-C emission, then the emission wavelength is in the desired UV-B or UV-C range, but the sheet resistance increases causing decreased light emission efficiency
Solution Approach 1:
The n-type semiconductor layer is divided into multiple layers with different Al compositions: a first n-type layer with lower Al composition (0.5≤x<0.65) having lower sheet resistance, and a second n-type layer with higher Al composition (x≥0.65) for UV-B/UV-C emission. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between emission wavelength and light emission efficiency.
2Illumination intensity
If the n-type semiconductor layer uses high Al composition (x≥0.65) for UV-B or UV-C emission, then the emission wavelength is in the desired UV-B or UV-C range, but the contact resistance with n-electrode increases causing increased forward voltage
Solution Approach 1:
The n-type semiconductor layer is segmented into a first n-type layer with lower Al composition that provides low contact resistance with the n-electrode, and a second n-type layer with higher Al composition that enables UV-B/UV-C emission. This segmentation resolves the contradiction between emission wavelength and forward voltage.
Solution Approach 2:
Different regions of the n-type semiconductor structure have different Al compositions optimized for their specific functions: the region contacting the n-electrode has lower Al composition for low contact resistance, while the light-emitting region has higher Al composition for UV-B/UV-C emission. This local quality differentiation resolves the contradiction between emission wavelength and forward voltage.
3Illumination intensity
If the n-type semiconductor layer uses high Al composition (x≥0.65), then UV-B or UV-C emission is achieved, but the light-emitting region is limited only to areas close to the n-electrode
Solution Approach 1:
The n-type semiconductor layer is segmented into a first n-type layer with lower Al composition that extends over a larger area with lower sheet resistance, and a second n-type layer with higher Al composition for UV-B/UV-C emission. This segmentation allows the light-emitting area to extend beyond regions close to the n-electrode, resolving the contradiction between emission wavelength and light-emitting area.
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 configuration enhances light emission efficiency and prevents increases in forward voltage by ensuring sufficient light emission across the chip area, even at high Al compositions for UV-B or UV-C emission.
Implementation Method 1
a light-emitting element, which is formed of a group III nitride semiconductor and emits light in a short wavelength range called UV-B or UV-C
Data Source
AI summary
A light-emitting element includes an n-type semiconductor layer mainly including AlxGa1−XN (0.5≤x≤1), a p-type semiconductor layer, a light-emitting layer sandwiched between the n-type semiconductor layer and the p-type semiconductor layer, an n-electrode connected to the n-type semiconductor layer, and a plurality of p-electrodes that are connected to the p-type semiconductor layer and are arranged in a dot pattern. An area of the n-electrode is not less than 25% and not more than 50% of a chip area.