VCSEL Heat Release Layer for Thermal Management
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Solution Overview
Problem
Conventional surface emitting laser devices for long wavelengths (1.3 to 1.6 μm) face challenges in heat release due to low thermal conductivity materials, leading to performance degradation and increased costs from complex fabrication methods involving wafer bonding of hetero-semiconductor wafers.
Innovation Solution
A surface emitting laser device is fabricated using a monolithic method where a heat release layer with higher thermal conductivity than the active and mirror layers is formed on the side surfaces of the active and mirror layers, using a dielectric and metal layer deposited via atomic layer deposition, and selectively etched to improve thermal properties and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fabrication methods using wafer bonding of hetero-semiconductor wafers are used to achieve long wavelength emission, then the laser can emit at required wavelengths, but the fabrication complexity and cost increase significantly
Solution Approach 1:
The patent combines the active layer and mirror layers into a single monolithic semiconductor structure grown on one substrate, eliminating the need for separate wafer bonding steps. This integration maintains long wavelength emission capability while dramatically simplifying the fabrication process.
Solution Approach 2:
The patent segments the laser structure into functionally distinct layers (active layer, mirror layers, cladding layers) that are all grown sequentially in a single epitaxial process, allowing complex functionality to be achieved through simple layer-by-layer growth without complex assembly steps.
2Adaptability or versatility
If materials with low thermal conductivity are used in the laser structure, then the desired optical properties can be achieved, but heat release becomes difficult leading to performance degradation
Solution Approach 1:
The patent introduces a heat release layer as an intermediary component between the active layer and the substrate. This layer has high thermal conductivity and acts as a thermal pathway to conduct heat away from the active region, solving the heat release problem without compromising the optical properties of the low thermal conductivity materials in the active and mirror layers.
Solution Approach 2:
The patent applies different thermal conductivity properties to different regions of the laser structure. The active layer and mirror layers use materials optimized for optical performance with lower thermal conductivity, while the heat release layer uses high thermal conductivity materials specifically in the region where heat needs to be conducted away, achieving local optimization of thermal management.
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 enhances thermal conductivity, improves reliability, and reduces costs by simplifying the fabrication process, enabling stable operation at ambient and high temperatures with improved productivity.
Implementation Method 1
a heat release layer having a higher thermal conductivity than those of the active and mirror layers
Implementation Method 2
using a dielectric and metal layer deposited via atomic layer deposition
Data Source
AI summary
Provided is a vertical cavity surface emitting device. The surface emitting device includes a lower mirror layer emitting light having a long wavelength, an active layer providing an optical gain, a tunnel junction layer for confining a current, and an upper mirror layer, which are sequentially stacked on a compound semiconductor substrate, wherein a heat release layer is formed on side surfaces of at least one of the active layer, the tunnel junction layer and the upper mirror layer by using etching process, and the heat release layer has greater thermal conductivity than at least one of the active layer, the tunnel junction layer and the upper mirror layer.