LED Quantum Well Indium Strain Compensation
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Solution Overview
Problem
Current semiconductor light sources, particularly laser diodes, face challenges in achieving uniformity and extending peak emission wavelengths beyond 1 μm due to strain issues and lattice relaxation, making them unsuitable for applications like IR inspection and medical diagnostics.
Innovation Solution
The development of light-emitting diodes (LEDs) with a 30% indium concentration quantum well and strain compensation using tensile stress barrier layers, along with a Bragg reflector, allows for the production of LEDs that emit in the 1.0 to 1.1 μm band, enhancing efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser diodes are used for IR inspection applications, then the peak wavelength can be achieved, but laser speckle, scatter and lack of uniformity cause difficulties
Solution Approach 1:
The patent extracts the harmful laser speckle and scatter effects by replacing laser diodes with LED technology, eliminating the coherent light source that causes these problems while maintaining the desired wavelength emission for IR inspection applications
Solution Approach 2:
The patent changes the light source type from laser diode to LED and adjusts the quantum well composition (InGaAs with specific indium content) to achieve the desired peak wavelength while providing uniform illumination without laser speckle and scatter effects
2Illumination intensity
If the indium content of the InGaAs strained quantum well is increased to extend wavelength beyond 1 μm, then the peak emission wavelength can be extended, but thickness approaches critical thickness causing defects and lattice relaxation
Solution Approach 1:
The patent changes the composition parameters of the quantum well by incorporating InGaAs with optimized indium content and thickness, allowing wavelength extension beyond 1 μm while maintaining layer thickness below the critical threshold to prevent defects and lattice relaxation
Solution Approach 2:
The patent uses composite material structures with multiple layers including InGaAs quantum wells embedded in GaAs cladding layers, where each layer is engineered with specific composition and thickness to achieve the desired optical properties while maintaining structural integrity
3Illumination intensity
If arrays of laser diodes are manufactured, then the desired wavelengths can be achieved, but manufacture is not practical
Solution Approach 1:
The patent replaces expensive and difficult-to-manufacture laser diodes with more economical LED technology that can be manufactured in arrays using standard semiconductor fabrication processes, making array production practical while maintaining the desired wavelength performance
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 manufacture of LED arrays that achieve desired wavelengths with improved efficiency and reduced defects, suitable for various applications including semiconductor inspection and medical diagnostics.
Implementation Method 1
an active layer having a quantum well of a thirty percent concentration of indium on the lower cladding layer
Implementation Method 2
strain compensation using tensile stress barrier layers, along with a Bragg reflector
Data Source
AI summary
A light-emitting diode includes a substrate, a lower cladding layer, an active layer having a quantum well of a thirty percent concentration of indium on the lower cladding layer, and an upper cladding layer. A method of manufacturing light-emitting diodes includes forming a lower cladding layer on a substrate, forming an active layer on the lower cladding layer such that the active layer has a quantum well of thirty percent indium, forming an upper cladding layer on the active layer, and forming a metal cap on the upper cladding layer.