Monolithic Laser Diode Chip Lattice Mismatch Reduction
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Solution Overview
Problem
Monolithically integrated laser diode chips with multiple beam construction face degradation due to local stresses and lattice mismatches between semiconductor substrates and waveguide or cladding layers, leading to impaired functionality and reduced lifetime.
Innovation Solution
Incorporating AlxGa1-xAs layers with additional elements from group III or V, such as phosphorus, indium, or nitrogen, to reduce lattice mismatches and stresses between the semiconductor substrate and waveguide or cladding layers, thereby enhancing lattice matching and reducing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard AlxGa1-xAs waveguide or cladding layers are used on GaAs substrate, then the laser diode chip can be manufactured with conventional processes, but local stresses and lattice mismatches arise between layers leading to degradation and reduced lifetime
Solution Approach 1:
The patent modifies the compositional parameters of the waveguide and cladding layers by incorporating additional elements (In, N, P) into the AlxGa1-xAs structure. This changes the lattice constant and thermal expansion properties of these layers to better match the GaAs substrate, thereby reducing lattice mismatch and thermal stress. Specifically, the composition is adjusted so that the lattice constant of the modified AlxGa1-xAs layer approximates that of GaAs, directly addressing the stress issue while maintaining the desired optical properties.
Solution Approach 2:
The patent creates composite semiconductor materials by combining AlxGa1-xAs with additional elements from group III (In) or group V (N, P). This results in a composite material structure such as AlxGa1-xInyAs1-zPzNw or similar compositions, where the combined material properties achieve both lattice matching with GaAs substrate and appropriate thermal expansion characteristics, thereby reducing interlayer stress and improving reliability.
2Reliability
If additional elements from group III or V are incorporated into AlxGa1-xAs layers, then lattice matching with GaAs substrate is improved and stresses are reduced, but the layer composition and manufacturing process become more complex
Solution Approach 1:
The patent systematically adjusts compositional parameters (x, y, z, w in AlxGa1-xInyAs1-zPzNw) to achieve optimal lattice matching with GaAs while maintaining manufacturability. By carefully controlling these parameters within specific ranges, the patent reduces lattice mismatch and stress without requiring completely new materials or processes, thus balancing improved reliability with manageable manufacturing complexity.
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 prolongs the lifetime of the laser diode chip by reducing local stresses and lattice mismatches, improving thermal stability, fracture quality, and overall reliability, while allowing for stable quasi-continuous operation with reduced current density and optical facet loading.
Implementation Method 1
the lattice mismatch between the at least one waveguide layer or cladding layer comprising the at least one additional element and the semiconductor substrate composed of GaAs is reduced
Implementation Method 2
The reduction of the lattice mismatches between the at least one waveguide layer or cladding layer and the semiconductor substrate results in a reduction of local stresses between the at least one waveguide layer or cladding layer and the semiconductor substrate
Data Source
AI summary
A monolithically integrated laser diode chip having a construction as a multiple beam laser diode, which, on a semiconductor substrate (3) comprised of GaAs, has at least two laser stacks (4a, 4b, 4c) which are arranged one above another and which each contain an active zone (7). The active zone (7) is in each case arranged between waveguide layers (8). The waveguide layers (8) each adjoin a cladding layer (6) at a side remote from the active zone. At least one of the waveguide layers (8) or cladding layers (6) of at least one laser stack (4a, 4b, 4c), comprises AlxGa1-xAs, where 0≦x≦1, and at least one additional material from main group III or V, such that the lattice mismatch between the at least one waveguide layer (8) or cladding layer (6) comprising the at least one additional element and the semiconductor substrate (3) composed of GaAs is reduced. This increases the lifetime of the laser diode chip.