LED Chip Cavity Capacitor ESD Protection Light Extraction
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Solution Overview
Problem
Light emitting diodes (LEDs) are prone to damage from electrostatic discharge (ESD) and suffer from reduced light extraction efficiency and reliability due to current crowding and absorption of light by electrodes in existing designs.
Innovation Solution
A light emitting device structure with capacitors formed in cavities within the LED chip, utilizing a dielectric layer and electrode configuration to manage ESD and enhance current spreading, thereby preventing damage and increasing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Zener diode is connected in parallel to the LED in reverse direction to prevent ESD damage, then the LED is protected from electrostatic discharge, but the absorption amount of light is decreased
Solution Approach 1:
The patent extracts the ESD protection function from a separate Zener diode component and integrates it directly into the LED structure by forming a capacitor within the LED chip itself. This eliminates the need for external ESD protection components that would block light, while maintaining the ESD protection function through the integrated capacitor structure.
Solution Approach 2:
The patent merges the ESD protection function with the LED structure by integrating a capacitor directly into the LED chip. The capacitor is formed within the same semiconductor substrate, combining the light-emitting function and ESD protection function into a single integrated device, thereby eliminating light absorption by separate protection components.
2Power
If an n-type electrode and p-type electrode are formed at upper and lower portions for current injection, then current can be injected into the LED, but light emitted from below the n-type electrode is absorbed or reflected by the electrode, decreasing light emitting efficiency
Solution Approach 1:
The patent applies local quality by creating cavities at specific locations where electrodes would otherwise absorb light. These cavities are strategically positioned to allow light to escape rather than being absorbed by the electrode, while the electrode structure is modified to have different properties in different regions - conductive where needed for current injection and non-absorptive where light passes through.
3Power
If electrodes are formed for current injection, then current can flow through the LED, but current crowding occurs which lowers the lifetime and reliability of the LED
Solution Approach 1:
The patent segments the current injection path by introducing cavities that distribute the current flow across multiple regions. Instead of current concentrating at a single electrode contact point, the cavity structure divides the current path into multiple segments, allowing more uniform current distribution throughout the active layer and reducing current crowding effects.
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 effectively prevents ESD damage, minimizes light absorption, and improves the reliability and efficiency of the LED by efficiently controlling current flow and buffering ESD impacts.
Implementation Method 1
capacitors respectively formed in parallel in a plurality of cavities defined by removing a portion of the light emitting structure
Implementation Method 2
during an electrostatic discharge (ESD), current flows in a reverse direction, so that an active layer that is a light emitting region may be damaged
Implementation Method 3
A light emitting device (LED) may be implemented by a p-n junction diode, which has the characteristic converting an electrical energy to a light energy
Implementation Method 4
electrons and holes respectively injected by the n-type electrode and the p-type electrode flow into an active layer and are recombined to thus generate light
Implementation Method 5
light extraction efficiency as well as current spreading efficiency
Implementation Method 6
light emitted from a layer below the n-type electrode is absorbed into or reflected by the n-type electrode, and thus light emitting efficiency may decrease
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Embodiments relate to a light emitting device (100), a light emitting device package (200), and a lighting system. The light emitting device (100) comprises: a light emitting structure (110) including a first conductive type semiconductor layer (102), an active layer (104) over the first conductive type semiconductor layer (102), and a second conductive type semiconductor layer (106) over the active layer (104); a dielectric layer (130) formed in each of a plurality of cavities defined by removing a portion of the light emitting structure (110); and a second electrode layer (120) over the dielectric layer (130).