Resonant Light-Emitting Element Electrode Structure Against Solder Diffusion
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Solution Overview
Problem
Surface light-emitting type light-emitting elements with a resonance mode layer experience a decrease in light output over time due to heat-induced diffusion of solder materials, leading to uneven surfaces and reduced light reflectance.
Innovation Solution
A multilayer metal electrode film structure is implemented, comprising a first layer for ohmic contact, a second layer for light reflection, a third layer with low solder diffusion, and a fourth layer for solder bonding, which blocks solder diffusion and maintains light reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a metal electrode film with a simple laminate structure is used, then the device complexity is reduced, but solder diffusion occurs leading to decreased light output over time
Solution Approach 1:
The metal electrode film is divided into multiple functional layers: a first metal layer for ohmic contact, a second metal layer for light reflection, and a third metal layer for solder bonding. This segmentation allows each layer to perform its specific function independently, preventing solder diffusion to the reflective layer while maintaining electrical and optical performance.
Solution Approach 2:
The structure uses the first metal layer as an intermediary between the semiconductor and solder, and the third metal layer as an intermediary between the second metal layer and solder. These intermediary layers block solder diffusion paths while allowing electrical conduction and optical reflection to function properly.
2Productivity
If the second layer reflects light effectively, then light output efficiency is improved, but solder diffusion to the second layer reduces reflectance over time
Solution Approach 1:
The third metal layer serves as a protective intermediary between the solder and the second metal layer. This intermediary layer has high solder diffusion resistance, blocking solder atoms from reaching and degrading the reflective surface of the second layer, thereby maintaining stable light reflectance over time.
Solution Approach 2:
The metal electrode film uses a composite multi-layer structure combining metals with different properties: the second layer uses a metal with high reflectance (such as Au, Ag, or Al), while the third layer uses a metal with high solder diffusion resistance (such as Pt, Pd, or Rh). This composite structure achieves both high light output efficiency and long-term stability.
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 multilayer metal electrode film structure effectively suppresses the chronological decrease in light output by preventing solder diffusion and maintaining light reflectance, ensuring stable light emission over time.
Implementation Method 1
The first layer is in close contact with the structure body via the first layer surface so as to form ohmic contact with the structure body
Implementation Method 2
The second layer has a composition different from that of the first layer, and reflects light from the resonance-mode forming layer
Implementation Method 3
The third layer has a composition different from that of the second layer, and has a lower diffusion degree than the second layer with respect to a diffusion degree of a solder material. The fourth layer has a composition different from that of the third layer, and has a higher diffusion degree than the third layer with respect to the diffusion degree of the solder material
Data Source
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AI summary
One aspect relates to a light-emitting element having a layer forming a resonance mode. The light-emitting element includes a structure body constituted by a substrate and a semiconductor laminate body including a first cladding layer, a second cladding layer, an active layer, and a resonance-mode forming layer including a basic layer and modified refractive index regions. A laser light output region and a metal electrode film are on opposing surfaces of the structure body. The metal electrode film includes a first layer forming ohmic contact with the structure body, a second layer reflecting light from the resonance-mode forming layer, a third layer, and a fourth layer for solder bonding. The third layer has a different composition from the second layer and the fourth layer, and has a lower diffusion degree than the second layer and the fourth layer to that of a solder material.