Micro LED Periphery Conductivity Control for Luminous Efficiency
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Solution Overview
Problem
Micro LEDs with sizes smaller than 50 μm suffer from current leakage and non-radiative re-combinations due to defective side walls, which reduce luminous efficiency, and existing solutions like altering metal electrode designs or using transparent electrodes do not adequately address these issues.
Innovation Solution
A micro light-emitting device with an epitaxial unit and a current-spreading layer, where the top portion has a periphery area with reduced conductivity formed through ion implantation or surface treatment, preventing current from flowing to the periphery and enhancing luminous efficiency by directing current flow to desired regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of micro LED is reduced to increase pixel density, then the pixel density is improved, but non-radiative re-combinations caused by defective side wall become more severe
Solution Approach 1:
The patent applies local quality by creating a non-ohmic contact region specifically at the periphery area of the epitaxial unit through ion implantation or surface treatment. This localized modification reduces conductivity only where needed (at the defective side wall periphery) while maintaining good ohmic contact in the central region, thus preventing non-radiative re-combinations at the edges without affecting the overall luminous efficiency of the micro LED
Solution Approach 2:
The patent changes the electrical conductivity parameter of the periphery area through ion implantation or surface treatment, transforming it from a high-conductivity ohmic contact region to a low-conductivity non-ohmic contact region. This parameter change effectively blocks current leakage at the defective side wall while maintaining the desired pixel density
2Ease of operation
If a metal electrode design is altered to improve current spreading, then current spreading effect is improved, but light absorption by metal electrode increases and luminous efficiency decreases
Solution Approach 1:
The patent applies local quality by spatially separating the current spreading function from the light-emitting region. The current-spreading layer is positioned only in the ohmic contact region (central area), while the periphery area maintains non-ohmic contact properties. This localized arrangement allows current spreading where needed without introducing light-absorbing metal electrodes in the light path
Solution Approach 2:
The patent introduces a current-spreading layer as an intermediary component that facilitates current distribution without directly contacting the light-emitting active layer. This intermediary layer enables improved current spreading while preventing direct metal-to-active-layer contact that would cause light absorption and reduce luminous efficiency
3Reliability
If a transparent electrode is used to change current path, then current leakage is reduced, but current spreading efficiency does not meet industrial requirements
Solution Approach 1:
The patent applies local quality by creating different contact properties in different regions: the periphery area has non-ohmic contact to prevent current leakage, while the central ohmic contact region provides excellent current spreading. This localized differentiation simultaneously achieves both current leakage prevention and high current spreading efficiency
Solution Approach 2:
The patent segments the contact structure into two distinct regions: a non-ohmic contact region at the periphery for preventing current leakage, and an ohmic contact region in the center for efficient current spreading. This segmentation allows each region to perform its specific function optimally, achieving both reliability and productivity requirements
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 improves luminous efficiency by preventing non-radiative re-combinations and increasing current density, ensuring effective current flow and stability in micro LEDs, thereby enhancing their performance.
Implementation Method 1
The periphery area has a reduced conductivity compared with the remainder of the top portion... subjecting the periphery area of the epitaxial unit to surface treatment so that the periphery area has a reduced conductivity
Data Source
AI summary
A micro light-emitting device includes an epitaxial unit and a current-spreading layer. The epitaxial unit has a top portion that includes an ohmic contact region and a non-ohmic contact region. The top portion has a periphery area which forms at least a part of the non-ohmic contact region. The periphery area has a reduced conductivity compared with the remainder of the top portion. The current-spreading layer is disposed on the ohmic contact region. A method for making the micro light-emitting device, and a display screen including the same are also disclosed.