LED Contact Interconnect Structures for Light Extraction and Current Spreading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state lighting devices, such as LEDs, face limitations in light emission efficiency due to internal reflection and current spreading issues, particularly in larger area LEDs, which affect the extraction of light and quantum efficiency.
Innovation Solution
The development of contact interconnect structures for LED chips, including contact plugs and interconnect segments that facilitate ohmic contact and extend through insulating layers, using materials like chromium, aluminum-doped zinc oxide, or indium tin oxide for the contact plugs and silver for reflective layers, with lateral extensions to enhance reflectivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If photons are internally reflected in a repeated manner, then light extraction efficiency is reduced, but quantum efficiency is improved through multiple reflection opportunities
Solution Approach 1:
The patent segments the internal reflection process by introducing a distributed mirror structure with multiple discrete reflective surfaces at different locations within the LED. This allows photons to be reflected at multiple controlled points rather than undergoing repeated random internal reflections, thereby improving light extraction efficiency while maintaining quantum efficiency through the segmented reflection path.
Solution Approach 2:
The patent introduces an intermediary distributed mirror structure composed of reflective surfaces that mediate between the active region and the external environment. These mirrors act as intermediaries to redirect photons that would otherwise undergo harmful repeated internal reflections, converting the harmful reflection mechanism into a controlled intermediate reflection process that improves overall light extraction.
2Reliability
If electrode surface area is increased to improve current spreading, then current distribution is improved, but device complexity increases
Solution Approach 1:
The patent transitions from planar electrode surfaces to three-dimensional distributed mirror structures with reflective surfaces oriented in multiple dimensions. This dimensional transformation allows current spreading functionality to be achieved through vertically stacked and angularly arranged reflective surfaces rather than requiring large lateral electrode expansions, thereby reducing device complexity while maintaining current distribution effectiveness.
Solution Approach 2:
The distributed mirror structure serves multiple functions simultaneously: it provides current spreading pathways, acts as reflective surfaces for light extraction, and creates additional optical cavities for photon management. This multi-functionality eliminates the need for separate dedicated current spreading electrodes, thereby reducing overall device complexity while achieving improved current distribution.
3Loss of energy
If contact interconnect structures are added to improve light extraction, then light emission efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the contact interconnect structures with the distributed mirror structures by integrating conductive materials directly into the mirror assembly process. This combining of electrical connection and optical reflection functions into a single integrated structure eliminates the need for separate manufacturing steps for contacts and mirrors, thereby reducing manufacturing complexity while maintaining improved light emission efficiency.
Solution Approach 2:
The patent employs composite materials that combine conductive and reflective properties within the same structural elements. By using materials that exhibit both electrical conductivity and optical reflectivity, the contact interconnect structures achieve dual functionality without requiring additional material layers or complex multi-material assembly processes, thereby simplifying manufacturing while improving light emission efficiency.
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 contact interconnect structures improve light extraction and quantum efficiency by reducing absorption and increasing reflectivity, leading to enhanced light emission and extended operational reliability of LEDs.
Implementation Method 1
contact plugs and various interconnect segments that provide electrical connections to certain layers of active LED structures. Exemplary interconnect structures include contact plugs at interfaces of the active LED structure for facilitating ohmic contact behavior
Implementation Method 2
Interconnect segments proximate the contact plug may have a same material as metal reflective layers used in other parts of the LED chip for increased reflectivity and improved reliability
Data Source
AI summary
Solid-state lighting devices including light-emitting diodes (LEDs) and more particularly contact interconnect structures for LED chips and related methods are disclosed. Contact interconnect structures include arrangements of contact plugs and various interconnect segments that provide electrical connections to certain layers of active LED structures. Exemplary interconnect structures include contact plugs at interfaces of the active LED structure for facilitating ohmic contact behavior, followed by multiple interconnect segments that extend through one or more insulating layers of LED chips. By providing multiple interconnect segments, materials used for the overall interconnect structure may be positionally varied. Interconnect segments proximate the contact plug may have a same material as metal reflective layers used in other parts of the LED chip for increased reflectivity and improved reliability. Interconnect segments may also be formed with lateral extensions that are embedded within the LED chip for further increased reflectivity.