Vertical LED Light Emitting Unit with Recessed Electrode
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Solution Overview
Problem
Vertical LEDs face a decrease in aperture ratio and light emission rate due to electrodes, leading to inefficient light emission.
Innovation Solution
A light emitting unit with an epitaxial structure featuring a light emission layer and semiconductor layers, where the second electrode is partially or fully disposed in a recess on the second type semiconductor layer, increasing the contacting area and enhancing current distribution and light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrodes are placed on the light emission side of vertical LED, then electron/hole mobility is enhanced, but aperture ratio is decreased
Solution Approach 1:
The patent transitions from planar electrode placement to three-dimensional recess embedding. The second electrode is positioned within a recess structure on the light emission side, utilizing the vertical dimension to accommodate the electrode without occupying lateral aperture space. This dimensional change allows the electrode to maintain electrical functionality while minimizing impact on light emission area.
Solution Approach 2:
The electrode is nested within the recess structure of the semiconductor layer. The second electrode is embedded inside the recess formed on the light emission side, creating a nested configuration where the electrode resides within the structural cavity. This nesting approach allows the electrode to be integrated into the device architecture without protruding into the aperture space.
2Reliability
If electrodes are placed on the light emission side of vertical LED, then current distribution is improved, but light emission rate is decreased
Solution Approach 1:
By moving the electrode placement from a surface-level configuration to a recess-embedded configuration, the patent achieves improved current distribution through enhanced contact area with the semiconductor layer, while simultaneously preserving light emission rate by keeping the electrode confined within the recess volume that does not obstruct the optical path.
Solution Approach 2:
The recess structure creates a localized region with enhanced electrical contact properties. The electrode embedded in the recess achieves superior current distribution locally at the contact interface, while the surrounding aperture region maintains its light emission properties. This local quality enhancement resolves the contradiction between electrical performance and optical performance.
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 improves light emission efficiency and current distribution by optimizing the placement of the second electrode within the recess, addressing the inefficiencies caused by electrode placement in vertical LEDs.
Implementation Method 1
Light emitting diode (LED) or organic light emitting diode (OLED) is applied in a variety of fields as a light emitting unit with high efficiency
Data Source
AI summary
A light emitting unit has a first electrode, a second electrode and an epitaxial structure disposed between the first electrode and the second electrode. The epitaxial structure has a light emission layer, a first type semiconductor layer disposed between the light emission layer and the first electrode, and a second type semiconductor layer disposed between the light emission layer and the second electrode. A first surface of the second type semiconductor layer is facing the light emission layer. The second type semiconductor layer has a second surface opposite to the first surface and the second surface has at least one recess. At least portion of the second electrode is disposed within the at least one recess. A display device has a substrate, a first electrode connection layer, a second electrode connection layer, and a plurality of aforementioned light emitting units.