LED Recess Structure for Uniform Current Injection in Displays
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Solution Overview
Problem
Current LED-based display devices face challenges in maintaining high luminance and manufacturing efficiency as they are miniaturized, with current leakage issues affecting the uniformity of current injection and leading to reduced luminance and increased power consumption.
Innovation Solution
A light-emitting device with a semiconductor structure that includes a recess in the undoped semiconductor layer and superlattice layer to expose a portion of the first semiconductor layer, reducing current leakage and improving injection efficiency, and a display device configuration with a light-emitting element featuring a protective layer on the side surfaces and electrodes directly contacting the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If LEDs are made smaller to reduce display device volume and increase pixel density, then the display device volume is reduced and pixel density is increased, but current injection uniformity deteriorates and luminance decreases
Solution Approach 1:
The patent applies local quality by creating a recess structure at specific locations (center or off-center) of the LED chip, modifying the local geometry to alter current distribution characteristics. This localized structural change allows smaller LED sizes while maintaining uniform current injection by concentrating current flow through the recess area, thereby resolving the contradiction between miniaturization and current injection uniformity.
2Productivity
If LEDs are made smaller to increase pixel density, then pixel density is increased, but current leakage to side surfaces increases and injection efficiency decreases
Solution Approach 1:
The recess structure creates a localized region with different electrical characteristics, concentrating current flow vertically through the light-emitting layer rather than allowing lateral leakage to side surfaces. This local modification enables higher pixel density while maintaining injection efficiency by guiding current through the desired path.
Solution Approach 2:
The patent introduces a vertical dimension (depth) to the LED structure by creating a recess, transforming the problem from a two-dimensional surface issue to a three-dimensional volume issue. This dimensional change allows control over current distribution by utilizing the vertical space within the recess to concentrate and guide current flow, preventing side surface leakage even at reduced LED sizes.
3Ease of manufacture
If conventional LED structure is used to simplify manufacturing, then manufacturing process is simple, but alignment defects and connection defects increase at smaller sizes
Solution Approach 1:
The recess structure is formed as a preliminary feature before electrode deposition, creating a built-in alignment reference that guides subsequent manufacturing steps. This pre-formed geometric feature serves as a physical guide for electrode placement, ensuring accurate alignment even when LEDs are miniaturized, thereby reducing alignment defects without complicating the overall manufacturing process.
Data Source
AI summary
A light-emitting device can include a semiconductor structure including a undoped semiconductor layer, a superlattice layer, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a protective layer disposed on a side surface of the semiconductor structure; a first electrode electrically connected to the first semiconductor layer; and a second electrode electrically connected to the second semiconductor layer. Also, a recess is formed in the undoped semiconductor layer and the superlattice layer, and the recess exposes a portion of a surface of the first semiconductor layer.