Monolithic Micro LED Peripheral Light Attenuation Structure
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Solution Overview
Problem
Conventional monolithic micro LED displays experience unintended light emission from their outer peripheral portions, leading to unwanted image display due to light reflection from the mesa side surfaces, which reduces the overall display quality.
Innovation Solution
A flip-chip monolithic micro LED design is implemented with a semiconductor layer structure that includes an n-layer, an active layer, and a p-layer, featuring a groove at the outer periphery to form a mesa shape and a light attenuation portion to reduce light emission from the outer peripheral area, utilizing a light shielding portion made of metal or a multilayer film for effective light attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mesa side surface is formed at the outer peripheral portion of the element, then light can be extracted from the side surface, but unintended light emission occurs from the outer peripheral portion
Solution Approach 1:
The patent converts the harmful light emission from the mesa side surface into a beneficial effect by applying a reflective film to the inner wall of the groove. This reflective film redirects the light that would otherwise be lost or cause unwanted emission back toward the light extraction surface, improving overall light extraction efficiency while eliminating the harmful peripheral emission.
Solution Approach 2:
The patent extracts the problematic light emission from the outer peripheral portion by introducing a groove structure that physically separates the light extraction path from the peripheral region. The groove acts as an optical isolator, taking out the harmful light emission component while preserving the desired light extraction function in the central region.
2Illumination intensity
If the outer peripheral portion emits strong light, then light extraction is enhanced, but an unintended image is displayed on the display
Solution Approach 1:
The reflective film applied to the groove inner wall converts the harmful strong light emission from the peripheral portion into a beneficial effect by redirecting this light toward the light extraction surface. This transforms the problematic high-intensity peripheral emission into useful light contribution while eliminating the unwanted image display effect.
Solution Approach 2:
The patent applies different optical properties to different regions: the groove inner wall receives a reflective film to redirect light, while the light extraction surface maintains its original light-emitting properties. This local differentiation of optical quality allows the peripheral region to contribute light without causing unwanted emission patterns.
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 significantly reduces light emission from the outer peripheral area, preventing unintended light display and enhancing the clarity of the intended image by attenuating light through the use of a strategically designed groove and light shielding portion, thereby improving the display quality.
Implementation Method 1
a reflective film is applied to an inner wall of the groove
Implementation Method 2
a light attenuation portion for attenuating light from the pixel is provided at an outer periphery of the light emitting element
Data Source
AI summary
A light emitting element, that is a flip-chip monolithic micro LED, includes a semiconductor layer including: an n-layer; an active layer located over the n-layer; and a p-layer located over the active layer, in which pixels are two-dimensionally arranged with a partial region of the semiconductor layer as one pixel, and a groove having a depth reaching the n-layer and making the semiconductor layer to have a mesa shape is formed at an outer periphery of the light emitting element, and a light attenuation portion for attenuating light from the pixel is provided at an outer periphery of the light emitting element.