Semiconductor Laser Fabrication via Void Formation
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Solution Overview
Problem
The existing semiconductor laser fabrication methods using photonic crystal structures with materials of smaller refractive indices than GaN face issues with uniformity due to deposition growth within holes, degrading the arrangement of voids and affecting the optical coupling and feedback efficiency.
Innovation Solution
A method involving the growth of an InX1Ga1−X1N layer, patterning to form openings, and subsequent growth of an AlX2Ga1−X2N layer to create voids without filling them, ensuring the side and bottom surfaces are made of InGaN, and optionally using a dielectric layer to enhance void formation and optical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photonic crystal structure is formed by patterning a GaN layer to create holes and growing a gallium nitride-based semiconductor over it, then the refractive index difference is large, but depositions grow within the holes deforming them and degrading the uniformity of the voids arrangement
Solution Approach 1:
The invention extracts the problematic material deposition step that causes hole deformation. Instead of filling holes with deposited material, the method removes the GaN layer selectively to create voids, eliminating the deposition-induced deformation issue entirely while maintaining the photonic crystal structure's refractive index contrast.
Solution Approach 2:
The invention inverts the conventional approach: instead of creating holes and then depositing material over them (which causes deformation), it creates holes and then selectively removes material to form voids. This inverted process eliminates the deformation problem while achieving the desired photonic crystal structure with high uniformity.
2Reliability
If materials with smaller refractive index than GaN are used to form photonic crystal layer, then the photonic crystal structure can be formed, but the uniformity is degraded due to deposition growth within holes
Solution Approach 1:
The invention extracts and eliminates the problematic deposition growth step that causes non-uniform void formation. By using selective removal instead of deposition, the method achieves both high optical coupling efficiency through maintained refractive index contrast and high uniformity of voids arrangement without deformation.
Solution Approach 2:
The invention changes the fundamental parameter of material formation from deposition (adding material) to selective removal (subtracting material). This parameter change eliminates the deformation mechanism while preserving the refractive index difference needed for optical coupling, thereby improving both reliability and manufacturing precision.
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 maintains the uniformity and optical coupling of the photonic crystal structure, enabling effective lasing oscillation with improved refractive index differences and reduced deformation of voids, thus enhancing the semiconductor laser's performance.
Implementation Method 1
growing, in a reactor, an InX1Ga1−X1N (0X1Ga1−X1N layer
Implementation Method 2
growing an AlX2Ga1−X2N (0≦X2≦1) layer on the top surface of the patterned InX1Ga1−X1N layer to form voids
Implementation Method 3
a photonic crystal layer is provided on the p-type cladding layer. The photonic crystal layer comprises a GaN epitaxial layer and portions made of a material having a smaller refractive index than that of GaN
Data Source
AI summary
There is provided a method of fabricating a semiconductor laser including a two-dimensional photonic crystal. The method comprises the steps of growing an InX1Ga1−X1N (0<X1<1) layer on a gallium nitride-based semiconductor region in a reactor; after taking out a substrate product including the InX1Ga1−X1N layer from the reactor, forming a plurality of openings for a two-dimensional diffraction grating of the two-dimensional photonic crystal in the InX1Ga1−X1N layer to form a patterned InX1Ga1−X1N layer; and growing an AlX2Ga1−X2N (0≦X2≦1) layer on a top surface of the patterned InX1Ga1−X1N layer to form voids associated with the openings.