III-Nitride DBR Cladding With AlScN for Lattice-Matched Confinement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in developing Group III-Nitride photonic devices lies in the crystalline lattice mismatch between the photonic waveguiding layer and the cladding layer, leading to high dislocation density and limited growth thickness, which affects the efficiency and compatibility of photonic modulators and lasers, especially at longer wavelengths.
Innovation Solution
The use of an Aluminum Scandium Nitride (Al1-xScxN) cladding layer with a refractive index smaller than the photonic waveguiding layer, allowing for lattice matching and reducing strain, enabling thicker DBR layers and improved optical mode propagation control, thus enhancing the efficiency of photonic modulators and lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cladding layer with lower refractive index is used, then optical mode confinement is achieved, but crystalline lattice mismatch causes high dislocation density and limits growth thickness
Solution Approach 1:
The patent changes the compositional parameter of the cladding layer by incorporating Scandium into Aluminum Nitride (Al1-xScxN), which simultaneously adjusts both the refractive index and lattice constant. This allows the cladding layer to maintain lower refractive index for optical confinement while having lattice constant closer to GaN, thereby reducing dislocation density and enabling thicker growth without compromising crystalline quality.
Solution Approach 2:
The patent uses composite material Al1-xScxN (Aluminum Scandium Nitride) that combines the advantages of AlN (wide bandgap, suitable refractive index) with Scandium addition (lattice matching capability). This composite material achieves both optical confinement function and improved crystalline quality by reducing lattice mismatch with the GaN waveguiding layer.
2Productivity
If the photonic waveguiding layer is made thicker to improve device performance, then optical efficiency increases, but lattice mismatch leads to increased dislocation density
Solution Approach 1:
By changing the compositional parameter x in Al1-xScxN cladding layer, the patent optimizes the lattice constant to be closer to GaN while maintaining suitable refractive index difference. This parameter adjustment enables growth of thicker photonic waveguiding layers with reduced dislocation density, thereby improving optical efficiency without sacrificing crystalline quality.
3Reliability
If AlN cladding layer is used to achieve wide bandgap and low refractive index, then optical confinement is improved, but lattice mismatch with GaN increases dislocation density
Solution Approach 1:
The patent modifies the AlN cladding layer by adding Scandium to create Al1-xScxN, which changes both the refractive index and lattice constant. The Scandium addition reduces the lattice constant closer to GaN, improving lattice matching and reducing dislocation density, while the refractive index remains sufficiently lower than GaN to maintain effective optical confinement.
Solution Approach 2:
The patent employs composite material Al1-xScxN that combines AlN's wide bandgap and suitable refractive index properties with Scandium's lattice-matching capability. This composite approach simultaneously achieves improved optical confinement and better lattice matching with GaN waveguiding layer.
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 allows for increased efficiency and flexibility in designing photonic devices, enabling operation across a broad spectral range from UV to near-infrared, with reduced dislocations and improved material quality, particularly for in-plane and vertical emitting lasers and modulators.
Implementation Method 1
the cladding layer having an index of refraction lower than the index of refraction of the photonic waveguiding layer at the operating wavelength of the photonic device to confine the photons within the photonic waveguiding layer
Data Source
AI summary
Photonic devices including a distributed Bragg reflector (DBR) having a stack of Group III-Nitride layers and Aluminum Scandium Nitride layers.