Micro LED Array Anti-Reflection Structure for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micro LED arrays face challenges in light extraction efficiency and cross-talk reduction due to the refraction and reflection of light at the interface between Group III-nitride light emitting devices and air, which affects their performance in high brightness applications.
Innovation Solution
A light emitting device array with a planar light emitting stack and anti-reflection layer, where the light emitting surface and contact surface are parallel, and an anti-reflection layer is used to increase light extraction efficiency, and an absorbing layer is employed to reduce cross-talk between adjacent devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a mesa structure is introduced to reduce active layer size, then device size is reduced, but processing complexity and alignment requirements increase
Solution Approach 1:
The device structure is segmented into distinct functional layers (substrate, buffer layer, active layer, cladding layer, anti-reflection layer) with the active layer laterally confined by the cladding layer, allowing size reduction without complex processing
Solution Approach 2:
The cladding layer serves multiple functions: it provides lateral confinement of the active layer, acts as a waveguide for light propagation, and eliminates the need for separate mesa etching structures, thereby reducing processing complexity while achieving compact device size
2Illumination intensity
If light is generated at high intensity for brightness applications, then luminance increases, but light reflection and cross-talk between adjacent devices increase
Solution Approach 1:
The anti-reflection layer converts harmful reflected light into beneficial extracted light by reducing reflection at the air-semiconductor interface, thereby increasing light extraction efficiency and reducing cross-talk between adjacent high-brightness devices
Solution Approach 2:
The refractive index parameter is changed by introducing the anti-reflection layer with intermediate refractive index between air and the Group III-nitride semiconductor, optimizing light extraction and minimizing reflection-induced cross-talk in high-luminance applications
3Ease of manufacture
If the light emitting surface is made parallel to the contact surface for simplified fabrication, then manufacturing ease increases, but light extraction efficiency decreases due to total internal reflection
Solution Approach 1:
The anti-reflection layer acts as an intermediary between the parallel light emitting surface and air, mediating the refractive index mismatch that causes total internal reflection, thereby maintaining fabrication simplicity while improving light extraction efficiency
Solution Approach 2:
A composite structure is formed by combining the Group III-nitride semiconductor layers with an anti-reflection layer material having different optical properties, creating a multi-layer composite that simplifies fabrication while enhancing light extraction through optimized optical impedance matching
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 enhances light extraction efficiency and reduces cross-talk between light emitting devices, improving the overall performance and brightness of the micro LED array by controlling the angles of light emission and absorption.
Implementation Method 1
The anti-reflection layer is configured to increase a light extraction efficiency of the light generated by the light emitting stack
Implementation Method 2
an absorbing layer is employed to reduce cross-talk between adjacent devices
Implementation Method 3
an active layer arranged between the first semiconducting layer and the second semiconducting layer, the active layer configured to generate light having a first wavelength
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A light emitting device array is provided. The light emitting device array comprises a light emitting stack, a first electrical contact layer, an array of second electrical contacts, and an anti-reflection layer. The light emitting stack has a light emitting surface and a contact surface. The light emitting surface and the contact surface define opposing sides of the light emitting stack. The light emitting stack comprises a plurality of Group III-nitride layers including a first semiconducting layer provided towards the light emitting surface of the light emitting stack, a second semiconducting layer provided towards the contact surface, and an active layer arranged between the first semiconducting layer and the second semiconducting layer, the active layer configured to generate light having a first wavelength. The light emitting surface and the contact surface are parallel to each other and aligned with the plurality of Group III-nitride layers. The first electrical contact layer is provided on the light emitting stack and is configured to be in electrical contact with the first semiconducting layer. The array of second electrical contacts is provided on the contact surface of the light emitting stack. Each second electrical contact defines a light emitting device between the first semiconducting layer and the second electrical contact. Each of the second electrical contacts is spaced apart from the other second electrical contacts to form a two-dimensional array of light emitting devices. The anti-reflection layer is provided on the light emitting surface. The anti-reflection layer is configured to increase a light extraction efficiency of the light generated by the light emitting stack.