Tunable LED via Tensile Stress Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting diode (LED) devices face manufacturing process degradation, leading to wavelength emission outside desired ranges, necessitating a method to tune the band-gap of the LED devices effectively.
Innovation Solution
A tunable light-emitting diode is achieved by incorporating a tensile-stressing layer on the base substrate with a plurality of quantum well layers, generating a predetermined level of tensile stress to adjust the band-gap, which is further enhanced by a spalling process to separate the LED structure from the host substrate, allowing for precise control over the wavelength of light emitted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the LED structure is formed on a host substrate using conventional methods, then the manufacturing process is straightforward, but the wavelength emission falls outside desired ranges due to manufacturing process degradation
Solution Approach 1:
The patent applies parameter changes by introducing a tensile-stressing layer that modifies the physical state of the quantum well layers through controlled tensile stress. This stress alters the band-gap energy of the InGaN quantum wells, thereby precisely tuning the wavelength emission. The stress level is controlled by adjusting the thickness and material composition of the tensile-stressing layer, enabling precise wavelength control below 250 nanometers while maintaining manufacturing reliability
Solution Approach 2:
The patent replaces conventional chemical composition tuning methods with a mechanical stress-based approach. Instead of relying solely on adjusting Indium content in InGaN quantum wells during epitaxial growth, the invention uses a tensile-stressing layer to apply mechanical stress that tunes the band-gap. This mechanical substitution provides more precise and reliable wavelength control, addressing the manufacturing precision issue while maintaining process simplicity
2Adaptability or versatility
If the band-gap is adjusted by changing the composition and thickness of quantum well layers, then the wavelength can be tuned, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the wavelength tuning function into two independent components: the quantum well layers provide the basic light-emitting structure, while a separate tensile-stressing layer provides the wavelength tuning capability. This segmentation allows the quantum well structure to remain relatively simple while achieving wavelength tunability through the additional stress layer, thereby reducing overall device complexity compared to heavily modified quantum well structures
Solution Approach 2:
The tensile-stressing layer acts as an intermediary between the substrate and the quantum well layers. Rather than directly modifying the quantum well composition and structure, the stress layer mediates the wavelength tuning through mechanical stress. This intermediary approach simplifies the quantum well structure while maintaining wavelength adaptability, as the stress layer can be adjusted independently to achieve desired emission wavelengths
3Ease of manufacture
If substrate spalling is performed to separate the LED structure from the host substrate, then the LED device is released, but additional manufacturing steps are required
Solution Approach 1:
The patent applies preliminary action by incorporating a spalling layer during the epitaxial growth process that pre-configures the structure for subsequent separation. This spalling layer is designed with specific properties that enable controlled fracture at a predetermined location. By preparing this separation mechanism in advance, the subsequent spalling step becomes a simple, rapid process that does not significantly impact manufacturing efficiency, while still achieving easy device release from the substrate
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
The solution enables precise adjustment of the band-gap and wavelength of light emitted by the LED devices, maintaining desired performance characteristics and ensuring the wavelength falls within a specific range, such as below 250 nanometers, through controlled stress levels between 300 megapascals and 2 gigapascals.
Implementation Method 1
a tensile-stressing layer formed on the base substrate and having a thickness and chemical composition configured to generate a first tensile stress in the base substrate, the first tensile stress selected to cause the base substrate to have a predetermined band-gap
Data Source
AI summary
A method of forming a light-emitting diode including determining a first level of tensile stress to be applied to a base substrate including a plurality of quantum well layers to adjust a band-gap of the base substrate to a predetermined band-gap. The first level of tensile stress is generated in the base substrate by forming a tensile-stressing layer on the base substrate.