Laser Chip Zinc Diffusion for Higher Mirror Damage Threshold
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Solution Overview
Problem
The existing methods for increasing the catastrophic optical mirror damage threshold in semiconductor laser devices are complicated and costly, with potential bonding or cohesive issues due to epitaxial growth processes.
Innovation Solution
A method involving photolithography steps to form window regions, followed by zinc diffusion through these regions using heat treatment, to increase the band gap width and reduce light absorption in the cavity surface, while avoiding mask cracking and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial re-growing is used to form wide band gap materials at the cavity surface, then the catastrophic optical mirror damage threshold is increased, but the process becomes more complicated and costly
Solution Approach 1:
The patent changes the material composition parameter by introducing wide band gap materials (AlGaAs or AlInGaAs) with specific aluminum content (15-30%) into the cladding layer through zinc diffusion, rather than using complex epitaxial re-growing. This parameter change achieves the same protective effect with a simpler process.
Solution Approach 2:
The patent replaces the mechanical/chemical epitaxial growth process with a thermal diffusion process. Zinc diffusion is performed by heating the structure to 600-700°C, allowing zinc atoms to diffuse and form the wide band gap material in-situ, substituting the complex epitaxial equipment and process with a simpler thermal treatment.
2Object-affected harmful factors
If epitaxial re-growing is used to form wide band gap materials, then light absorption is reduced, but bonding or cohesive problems occur affecting device performance
Solution Approach 1:
The patent extracts the wide band gap material formation from the complex epitaxial re-growing process and achieves it through zinc diffusion into the existing cladding layer. This takes out the problematic bonding interface creation and replaces it with a diffusion-based in-situ formation, eliminating cohesive issues while maintaining the light absorption reduction effect.
Solution Approach 2:
Zinc acts as an intermediary element that, when diffused into the GaAs cladding layer, forms AlGaAs or AlInGaAs wide band gap material. This intermediary approach allows the transformation of the cladding layer properties without requiring separate epitaxial growth of additional layers, avoiding bonding problems.
3Ease of manufacture
If the window region is directly formed on the contact layer without mask protection, then the process is simplified, but mask cracking occurs due to thermal stress
Solution Approach 1:
The patent performs preliminary etching to form the window region exposing the cladding layer before the zinc diffusion process. This preliminary action defines the diffusion area in advance, so that during the subsequent high-temperature diffusion, the mask only needs to protect areas outside the pre-defined window, reducing thermal stress concentration and preventing mask cracking.
Solution Approach 2:
The patent segments the processing into distinct steps: first etching the window region, then applying mask, then diffusion. This segmentation allows the mask to be applied only where needed and reduces the overall thermal stress burden on the mask structure, preventing cracking while maintaining process simplicity.
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
Enhances the catastrophic optical mirror damage threshold, improves the laser chip's lifetime and quality by reducing local light absorption, and simplifies the preparation process.
Implementation Method 1
diffusing the zinc particle of the zinc diffusion layer to the cladding layer and the active layer by heat treatment
Implementation Method 2
diffusing the zinc particle of the zinc diffusion layer to the cladding layer and the active layer by heat treatment
Data Source
AI summary
Disclosed in the present invention are a laser chip and a preparation method therefor. Said method comprises: providing a laser epitaxial structure, the laser epitaxial structure comprising an active layer, and a cladding layer and a contact layer which are sequentially stacked on the active layer; covering a first mask layer on the contact layer, and a photolithograph step is performed on the first mask layer to form a first window region; performing primary etching on the contact layer by means of the first window region, so as to form a second window region corresponding to the first window region and exposing the cladding layer; performing zinc diffusion on the cladding layer and the active layer by means of the first window region and the second window region; removing the first mask layer; covering a second mask layer on the contact layer, and a photolithograph step is performed on the second mask layer to form a third window region, the projection of the third window region on the contact layer being located at the periphery of the second window region; and performing secondary etching on the contact layer by means of the third window region, so as to enlarge the second window region to correspond to the third window region. The described method can effectively increase a catastrophic optical mirror damage threshold.