Light-Emitting Element Electrode Stack for Reflectance Preservation
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Solution Overview
Problem
The existing light-emitting elements face a challenge in improving light extraction efficiency due to heat treatment affecting the reflectance of metal reflective films, which reduces light reflectance and overall efficiency.
Innovation Solution
A method involving the formation of a light-transmissive insulating film, a first light-transmissive electrode, a metal film, and a second light-transmissive electrode, where the second electrode is electrically connected to the first and covers the metal film, with the p-pad electrode in contact with the second electrode, enhancing light extraction by reducing absorption and maintaining reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed after forming the light-transmissive electrodes to improve ohmic contact and light transmittance, then electrical conductivity and light transmittance are improved, but light reflectance of the metal reflective films decreases
Solution Approach 1:
The metal reflective film is formed before the heat treatment process. By performing the preliminary action of depositing the metal film early in the manufacturing sequence, the film is positioned to receive the beneficial effects of subsequent heat treatment (improved ohmic contact) without being degraded by it, thereby preserving light reflectance while achieving electrical conductivity improvement.
Solution Approach 2:
The light-transmissive electrode structure is divided into multiple segments: a first light-transmissive electrode formed before heat treatment, and a second light-transmissive electrode formed after heat treatment. This segmentation allows each electrode to serve different functions - the first provides ohmic contact after heat treatment, while the second provides light extraction path without being degraded by heat treatment.
2Loss of energy
If metal reflective films are disposed above insulating films to reduce light absorption by p-pad electrodes, then light absorption by p-pad electrodes is reduced, but light extraction efficiency has room for further improvement
Solution Approach 1:
The light extraction path is extended into a new dimension by forming the second light-transmissive electrode above the metal reflective film. This creates an additional optical pathway that allows light to be extracted through the metal film region, thereby improving overall light extraction efficiency while the metal film continues to prevent light absorption by the p-pad electrode.
Solution Approach 2:
The second light-transmissive electrode acts as an intermediary element between the metal reflective film and the external environment. It enables light to pass through the region above the metal film without being absorbed, effectively mediating the optical interaction and improving light extraction efficiency while maintaining the light-blocking function for the p-pad electrode.
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 configuration improves light extraction efficiency by minimizing light absorption and maintaining reflectance, leading to enhanced performance in light-emitting elements.
Implementation Method 1
heat treatment may be performed after forming the light-transmissive electrodes in order to improve ohmic contact with the p-side semiconductor layers
Implementation Method 2
metal reflective films are disposed above the insulating films... light absorption by the p-pad electrode can be reduced
Implementation Method 3
a first light-transmissive electrode to continuously cover an upper surface of the semiconductor layered body... a second light-transmissive electrode to continuously cover an upper surface of the metal film and an upper surface of the first light-transmissive electrode
Data Source
AI summary
A method of manufacturing a light-emitting element includes forming a light-transmissive insulating film on a portion of an upper surface of a semiconductor layered body; forming a first light-transmissive electrode to continuously cover the upper surface of the semiconductor layered body and an upper surface of the light-transmissive insulating film; heat-treating the first light-transmissive electrode, and subsequently forming a metal film in at least a portion of a region above the light-transmissive insulating film; forming a second light-transmissive electrode to continuously cover an upper surface of the metal film and an upper surface of the first light-transmissive electrode, the second light-transmissive electrode being electrically connected to the first light-transmissive electrode; and forming a pad electrode in a region where the metal film is disposed in a top view, such that at least a portion of the pad electrode is in contact with an upper surface of the second light-transmissive electrode.