LED Connector Placement with DBR Insulation Layer
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Solution Overview
Problem
Conventional light emitting diode (LED) fabrication methods face issues such as short circuits due to metallic etching by-products, damage to reflective metal layers, and optical losses due to substrate absorption and connector absorption of light, which affect luminous efficiency and reliability.
Innovation Solution
The solution involves a light emitting device with connectors located between the substrate and cells, featuring insulation layers with distributed Bragg reflectors (DBR) to prevent short circuits and optical losses, and holes in the cells to facilitate current spreading and connector placement, enhancing luminous efficiency and preventing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connectors are placed directly on the substrate to connect light emitting cells, then electrical connection is achieved, but light is absorbed by the substrate and connectors causing optical loss
Solution Approach 1:
An insulation layer with distributed Bragg reflector (DBR) structure is introduced as an intermediary between the connectors and the substrate. This DBR layer reflects light that would otherwise be absorbed by the substrate and connectors back into the light emitting cells, thereby reducing optical loss while maintaining electrical connectivity
Solution Approach 2:
The insulation layer is designed with specific optical parameters (refractive index and thickness) to create a distributed Bragg reflector that reflects specific wavelengths of light. By changing the optical parameters of the insulation layer, the reflectivity is optimized to minimize light absorption by the substrate and connectors
2Manufacturing precision
If photolithography and etching are used to pattern semiconductor layers and metal layers, then precise patterning is achieved, but metallic etching by-products cause short circuits between N-type and P-type semiconductor layers
Solution Approach 1:
The insulation layer with DBR structure is formed beforehand before the photolithography and etching processes. This preliminary insulation layer prevents metallic etching by-products from causing short circuits between the N-type and P-type semiconductor layers, while still allowing precise patterning to be achieved
Solution Approach 2:
The insulation layer acts as an intermediary barrier that prevents direct contact between metallic etching by-products and the semiconductor layers. This intermediary layer eliminates the harmful effect of metallic by-products causing short circuits while maintaining the benefits of photolithography and etching for precise patterning
3Loss of energy
If reflective metal layer is used to reflect light, then light extraction efficiency is improved, but the metal layer surface is damaged by plasma during etching
Solution Approach 1:
The reflective metal layer is formed before the etching processes. This preliminary formation allows the metal layer to be protected during subsequent etching operations, preventing plasma damage while maintaining its light reflecting capability
Solution Approach 2:
The insulation layer with DBR structure is introduced as a protective cushion before the etching processes. This beforehand protection prevents plasma from directly contacting and damaging the reflective metal layer surface, thereby preserving the metal layer's light reflecting efficiency
4Ease of manufacture
If holes are formed through semiconductor layers to expose upper semiconductor layer, then connector connection is facilitated, but current spreading may be disrupted
Solution Approach 1:
Holes are formed at specific local positions (central regions) of the light emitting cells to expose the upper semiconductor layer. This localized hole formation facilitates connector connection at specific points while minimizing disruption to current spreading paths in other regions
Solution Approach 2:
The holes provide vertical connectivity (another dimension) through the semiconductor layers, allowing connectors to reach the upper semiconductor layer from below. This dimensional approach facilitates connector placement without requiring lateral disruption to the current spreading structure
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
This approach prevents electrical short circuits, reduces light loss, and improves luminous efficiency by reflecting light back into the device and ensuring effective current distribution across the light emitting cells.
Implementation Method 1
insulation layers with distributed Bragg reflectors (DBR) to prevent short circuits and optical losses, and holes in the cells to facilitate current spreading and connector placement, enhancing luminous efficiency and preventing light absorption
Implementation Method 2
improves luminous efficiency by reflecting light back into the device
Data Source
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AI summary
Disclosed are a light emitting device and a method of fabricating the same. The light emitting device includes a substrate; first and second light emitting cells, each including a first conductive type upper semiconductor layer, an active layer, a second conductive type lower semiconductor layer, and a hole formed through the second conductive type lower semiconductor layer and the active layer to expose the first conductive type upper semiconductor layer; and a connector located between the first and second light emitting cells and the substrate and electrically connecting the first and second light emitting cells to each other. The holes are located at central regions of the first and second light emitting cells, respectively, and the connector electrically connects the second conductive type lower semiconductor layer of the first light emitting cell to the first conductive type upper semiconductor layer exposed in the hole of the second light emitting cell. Since the connector is located between the substrate and the light emitting cells, it is possible to prevent loss of light by the connector. Further, since the holes are located at the central region of the light emitting cells, the connector can be connected to the first conductive type upper semiconductor layer at the central region, thereby allowing current spreading over a wide area of the light emitting cells.