Group III-V Quantum Well Laser Diode Wavelength Control
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Solution Overview
Problem
Current semiconductor laser diodes lack effective control over emission wavelength in the green-yellow-orange spectrum range, leading to complex and inefficient solutions for achieving high-quality light emission, particularly in the 530-635 nm range, which is crucial for various applications including solid-state lighting and optical communications.
Innovation Solution
The method involves depositing a dielectric layer on semiconductor quantum well laser diodes and annealing at elevated temperatures to induce strain, allowing for a blue-shift in emission wavelength, effectively modifying the emission to orange or yellow by 20 meV to 350 meV, using techniques like molecular beam epitaxy or metal-organic chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If frequency doubling of diode-pumped solid state lasers is used to achieve orange, yellow and green emission, then the desired wavelength range can be accessed, but the system becomes more complex requiring non-linear crystals, external distributed Bragg reflector and heat sink
Solution Approach 1:
The patent extracts and eliminates the complex external components (non-linear crystals, distributed Bragg reflectors, heat sinks) by integrating the wavelength conversion function directly into the laser diode structure through quantum well engineering. The quantum well composition and strain are optimized to directly emit in the green-yellow-orange range without requiring external frequency doubling equipment.
Solution Approach 2:
The laser diode structure is designed to perform multiple functions within a single integrated device: generating light, confining carriers, and achieving the desired wavelength emission through quantum well design. The (Al,Ga,In)P quantum well system provides both the light emission and wavelength control functions that previously required separate external components.
2Temperature
If InGaN/GaN quantum well structure is used for green-yellow-orange emission, then the desired spectrum can be covered, but large strain and indium segregation prevent growth of high quality light emitting devices
Solution Approach 1:
The patent changes the material composition parameters by using (Al,Ga,In)P quantum wells instead of InGaN/GaN. This compositional change allows achieving green-yellow-orange emission (530-635 nm) without the strain and segregation problems that plague InGaN-based devices in this wavelength range.
Solution Approach 2:
The patent employs composite (Al,Ga,In)P material system combining aluminum gallium phosphide with indium phosphide to create quantum wells that emit in the green-yellow-orange range. This composite material approach provides both the desired wavelength emission and maintains high device quality without the defects associated with alternative material systems.
3Temperature
If InGaP/InAlGaP system is used for green-yellow-orange emission, then the desired spectrum can be covered, but small band offset leads to small carrier confinement and large carrier leakage
Solution Approach 1:
The patent optimizes the band offset parameters by carefully designing the (Al,Ga,In)P quantum well composition and barrier structure. The quantum well composition is tuned to achieve both the desired green-yellow-orange emission wavelength and sufficient band offset for effective carrier confinement, eliminating the carrier leakage problem in InGaP/InAlGaP systems.
4Temperature
If external pressure technique is applied to blue-shift emission wavelength, then the desired wavelength range can be achieved, but the lasers are non-practical for commercial applications due to high power consumption
Solution Approach 1:
The patent performs preliminary action during the laser diode fabrication process by designing quantum wells with specific composition and strain characteristics that inherently produce blue-shifted emission in the green-yellow-orange range. This eliminates the need for external pressure application during operation, thereby avoiding the high power consumption associated with pressure techniques.
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 enables the production of semiconductor quantum well laser diodes with controlled emission wavelengths in the desired range, enhancing their efficiency and practicality for commercial applications by simplifying the manufacturing process and reducing power consumption.
Implementation Method 1
the dielectric layer has a thickness effective to induce a strain in the quantum well layer
Implementation Method 2
annealing the quantum well laser diode at an elevated temperature with respect to room temperature for a period of time sufficient to relax at least some of the strain in the quantum well layer
Data Source
AI summary
Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.