Multi-Active-Layer LED Structure for Uniform Emission Control
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Solution Overview
Problem
In micro LED displays, it is challenging to uniformly control active layers due to differences in drive voltage, current injection efficiency, and reverse current caused by varying pn junction distances, and forming high-quality InGaN layers for green or red light emission is difficult due to lattice mismatch and thermal damage.
Innovation Solution
A light emitting element with a group-III nitride semiconductor structure that includes an n-layer, active layers with different emission wavelengths, an intermediate layer with a non-doped and n-type layer configuration, and a p-layer structure to reduce diode characteristic differences and improve surface flatness and quality, using a growth temperature of 700° C. to 1000° C. to form the intermediate layer and adjusting the In composition to prevent thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the intermediate layer is formed at a low temperature to avoid thermal damage to the active layer, then thermal damage is prevented, but the quality and surface flatness of the intermediate layer are deteriorated
Solution Approach 1:
The patent changes the temperature parameter from low temperature (conventional) to high temperature (700-1000°C) to improve the surface flatness and quality of the intermediate layer. This parameter change resolves the contradiction by prioritizing surface quality over thermal damage prevention, as the high temperature forms a flatter intermediate layer that improves overall device performance.
2Illumination intensity
If the In composition ratio is increased to emit green or red light, then the emission wavelength is achieved, but strain occurs due to lattice mismatch and high-quality InGaN cannot be formed
Solution Approach 1:
The patent changes the growth temperature parameter to 700-1000°C, which allows for the formation of high-quality InGaN layers with high In composition ratios (35% or more) required for green and red light emission. This temperature optimization reduces strain and lattice mismatch issues, enabling both the desired emission wavelength and high layer quality.
3Ease of operation
If the pn junction distance is varied for different active layers, then individual layer driving is enabled, but differences in drive voltage, current injection efficiency, and reverse current occur
Solution Approach 1:
The patent introduces an intermediate layer as a mediator between active layers. This intermediate layer with optimized thickness and composition helps to equalize the pn junction distances for different active layers, thereby reducing differences in drive voltage, current injection efficiency, and reverse current while still allowing individual layer control through selective electrode connection.
Data Source
AI summary
A first intermediate layer is a semiconductor layer provided on a first active layer, and is positioned between the first active layer and a second active layer. The first intermediate layer is structured so that a non-doped layer and an n-type layer are laminated in the order from the first active layer side. A second intermediate layer is a semiconductor layer provided on the second active layer, and is positioned between the second active layer and the third active layer. The second intermediate layer is structured so that a non-doped layer and an n-type layer are laminated in the order from the second active layer side.