Monolithic Micro LED Absorbing Structure for Higher Pixel Contrast
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Solution Overview
Problem
Conventional monolithic micro LED displays face issues with reduced contrast due to light reflection and transmission across pixels, leading to incorrect light emission and reduced image quality.
Innovation Solution
A flip-chip mounted monolithic micro LED display element is designed with a substrate, n-type, light-emitting, and p-type layers, along with a unique absorbing structure composed of alternately deposited dielectric and metal films. This structure absorbs light reflections and transmissions, enhancing contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a common substrate with transparent electrodes and insulating films is used for monolithic micro LED, then device integration is achieved, but light reflection and transmission occur causing reduced contrast between pixels
Solution Approach 1:
The patent applies black chromium (Cr) coating to the transparent electrodes and insulating films. This converts the harmful light reflection and transmission into beneficial light absorption. The black Cr layer has high light absorption properties that prevent light from reflecting or transmitting between pixels, thereby improving contrast while maintaining the integrated device structure.
Solution Approach 2:
The black chromium layer acts as an intermediary substance between the transparent electrodes/insulating films and the light. It mediates the light interaction by absorbing stray light that would otherwise reflect or transmit through the transparent components, preventing cross-talk between pixels while allowing the transparent electrodes to maintain their electrical function.
2Object-affected harmful factors
If separating spaces are created between light-emitting parts to prevent light transmission, then contrast is improved, but device miniaturization becomes difficult
Solution Approach 1:
Instead of creating physical separating spaces, the patent uses black chromium coating to absorb light. This converts the approach from spatial separation to optical absorption, allowing pixels to be placed closer together without light transmission between them, thereby maintaining small device size while improving contrast.
3Object-affected harmful factors
If etching is performed to separate semiconductor regions for each pixel, then light transmission is prevented, but manufacturing time increases
Solution Approach 1:
The patent applies black chromium coating to the insulating films and electrodes instead of performing etching to create separation trenches. This eliminates the time-consuming etching process while still preventing light transmission between pixels through optical absorption, significantly reducing manufacturing time while maintaining contrast.
4Device complexity
If a p-type contact layer is commonly formed among light-emitting parts to simplify structure, then device complexity is reduced, but current diffusion occurs causing adjacent pixels to emit light and contrast to decrease
Solution Approach 1:
The patent uses black chromium coating on the transparent electrodes and insulating films to absorb light. This prevents light from adjacent pixels that might be caused by current diffusion, thereby maintaining contrast even with a commonly formed p-type contact layer. The black Cr layer compensates for the current diffusion issue by absorbing any light that leaks from adjacent regions.
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 proposed solution effectively absorbs light reflections and transmissions, significantly improving contrast between pixels, ensuring accurate light emission and enhanced image quality in micro LED displays.
Implementation Method 1
an absorbing structure absorbing light disposed on or above the first electrode
Data Source
AI summary
The present invention provides a flip-chip mounted monolithic micro LED having improved contrast. The light-emitting device includes a substrate, an n-type layer, a light-emitting layer, a p-type layer, a transparent electrode, a p-electrode, an n-electrode, a protective film, an absorbing structure, and a side wall insulating film. The absorbing structure is a layered body in which a dielectric film and a metal film are alternately deposited, and the top layer is a dielectric film. Reflected light of light emitted from the light-emitting layer or reflected light of light from the outside, or transmitted light from the backside of the substrate can be absorbed by the absorbing structure, thereby improving contrast.