Micro-LED Current Limiting Layer for Sidewall Recombination Control
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Solution Overview
Problem
The shrinking size of micro light-emitting elements in display devices leads to a significant decrease in luminous efficiency due to non-radiative recombination caused by defects at the sidewall surface during the etching process, known as the size effect (micro-LED size effect).
Innovation Solution
A light emitting device structure is developed with a first current limiting layer having a higher oxygen content in its oxidizing region compared to its non-oxidizing region, positioned between the active layer and the contact layer, which limits the current path away from the sidewall and suppresses non-radiative recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of micro light-emitting elements is continuously shrunk to achieve high-resolution displays, then the display resolution is improved, but the luminous efficiency significantly decreases due to non-radiative recombination at sidewall defects
Solution Approach 1:
The patent applies local quality by creating distinct oxidizing and non-oxidizing regions within the current limiting layer. The non-oxidizing region is specifically positioned at the sidewall area to reduce defect formation, while the oxidizing region is located in the light-emitting area to maintain high luminous efficiency. This spatial differentiation of material properties allows the device to simultaneously achieve small size for high resolution and high luminous efficiency by optimizing each region's characteristics for its specific function.
2Manufacturing precision
If the device size is reduced, then the display pixel density is improved, but the ratio of perimeter to light emitting area increases causing more sidewall defects
Solution Approach 1:
The patent addresses the increased sidewall defect problem in miniaturized devices by implementing local quality through a current limiting layer with spatially varying oxidation states. The non-oxidizing region is specifically targeted at the sidewall area where defects commonly form during etching, reducing carrier non-radiative recombination. This localized treatment allows the device to maintain high pixel density with reduced sidewall impact.
Solution Approach 2:
The current limiting layer serves as an intermediary structure between the active layer and contact layer, with its non-oxidizing region acting as a protective buffer at the sidewall. This intermediary layer mediates the interaction between carriers and sidewall defects, preventing direct contact and reducing harmful non-radiative recombination effects that would otherwise dominate in miniaturized devices.
3Ease of operation
If carriers diffuse to the sidewall during operation, then the current distribution is affected, but non-radiative recombination increases reducing luminous efficiency
Solution Approach 1:
The patent uses local quality by creating a non-oxidizing region with distinct material properties at the sidewall area of the current limiting layer. This region has reduced oxygen content compared to the oxidizing region, which suppresses non-radiative recombination of carriers that diffuse toward the sidewall. The spatially differentiated structure allows carriers to maintain proper distribution while minimizing energy loss at the sidewall interface.
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 effectively improves the luminous efficiency of the light emitting device by confining the current path in the non-oxidizing region, reducing non-radiative recombination and enhancing radiative recombination rates.
Implementation Method 1
The first current limiting layer is disposed between the first contact layer and the active layer... The first oxidizing region is extended from the first surface to the second surface, and an oxygen content of the first oxidizing region is greater than an oxygen content of the first non-oxidizing region
Implementation Method 2
the phenomenon of non-radiative recombination caused by the diffusion of carriers to the sidewall of the device is suppressed
Data Source
AI summary
A light emitting device including an active layer, a first semiconductor layer, a first contact layer, and a first current limiting layer is provided. The first semiconductor layer is disposed at a first side of the active layer. The first contact layer is disposed at a side of the first semiconductor layer away from the active layer. The first current limiting layer is disposed between the first contact layer and the active layer, and is provided with a first non-oxidizing region and a first oxidizing region located around the first non-oxidizing region. The first current limiting layer has a first surface facing the active layer and a second surface away from the first surface. The first oxidizing region is extended from the first surface to the second surface, and an oxygen content of the first oxidizing region is greater than an oxygen content of the first non-oxidizing region.