Semiconductor Optical Device Thermal Management via High-Conductivity Cladding
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Solution Overview
Problem
Semiconductor optical devices face challenges in achieving both high thermal conductivity and light confinement, particularly due to limitations in materials like InP and GaAs, which hinder high injection current operation and efficient heat dissipation, and integration with Si leads to thermal stress and defects.
Innovation Solution
A semiconductor optical device configuration with a cladding layer made of materials like SiC, GaN, or C, having higher thermal conductivity, lower refractive index, and larger band gap than the core and cladding layers, along with a thin insulating film for optimal light confinement and heat dissipation, allowing for efficient current injection and electric field application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If compound semiconductor materials such as InP or GaAs are used for the active layer, then light emission is achieved, but thermal conductivity is poor leading to temperature rise during operation
Solution Approach 1:
The patent introduces a substrate made of material with high thermal conductivity (such as SiC, diamond, or GaN) as an intermediary between the compound semiconductor active layer and the heat sink. This substrate acts as a thermal mediator that conducts heat away from the active layer efficiently while allowing the active layer to maintain its light-emitting properties. The substrate serves as a bridge that resolves the contradiction between maintaining low temperature for operation and achieving high light emission that generates heat.
2Temperature
If Si is used as substrate material for high thermal conductivity, then heat dissipation is improved, but refractive index is higher than InP/GaAs making light confinement difficult
Solution Approach 1:
The patent applies local quality by using different materials with optimized properties for different functional regions. The substrate uses Si or SiC for high thermal conductivity in the heat dissipation region, while the cladding layer uses materials with lower refractive index than the active layer for light confinement. This spatial differentiation of material properties allows simultaneous achievement of heat dissipation and light confinement without compromise.
3Illumination intensity
If air or insulating film is used as cladding material to increase refractive index difference, then light confinement is improved, but thermal conductivity is deteriorated leading to greater temperature rise
Solution Approach 1:
The patent introduces a cladding layer made of semiconductor material with lower refractive index than the active layer as an intermediary structure. This cladding layer provides sufficient light confinement through refractive index difference while maintaining thermal conductivity pathways. The cladding layer acts as a mediator that resolves the contradiction between optical confinement requirements and thermal management requirements, allowing both functions to coexist effectively.
4Temperature
If metal material such as Au is used for high thermal conductivity, then heat conduction is improved, but absorption loss of light is large preventing light confinement
Solution Approach 1:
The patent changes the material parameter selection by avoiding metals entirely and using semiconductor materials (SiC, GaN, diamond, or compound semiconductors) for the substrate and cladding layers. These materials have the unique property of having both high thermal conductivity and low optical absorption loss at the operating wavelength. This parameter change in material selection resolves the contradiction between thermal conductivity and optical transparency, as semiconductor materials simultaneously satisfy both requirements whereas metals fail the optical requirement.
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 enables efficient heat dissipation, high light confinement, and withstands high temperature processing, allowing for higher injection currents and faster direct modulation while minimizing thermal stress and defects.
Implementation Method 1
the third cladding layer is made of a material having: a thermal conductivity greater than that of any of the first core layer, the first cladding layer, and the second cladding layer
Implementation Method 2
a refractive index smaller than that of any of the first core layer, the first cladding layer, and the second cladding layer
Data Source
AI summary
A semiconductor optical device that achieves both of heat dissipation and light confinement and permits efficient current injection or application of an electric field is implemented. The semiconductor optical device includes: a core layer including an active region (1) made of a compound semiconductor; two cladding layers (5, 6) injecting current into the core layer; and a third cladding layer (4) made of a material having a larger thermal conductivity, a smaller refractive index, and a larger band gap than a material for any of the core layer and the two cladding layers.