Broadband Blue LED Epitaxial Structure for Stable White Spectrum
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Solution Overview
Problem
Conventional blue light-emitting diodes (LEDs) generate white light with unstable spectrum waveforms at the blue wavelength band, leading to fluctuations in color rendering index when the operating current changes, failing to meet practical application requirements.
Innovation Solution
A light-emitting diode with an epitaxial structure featuring a light-emitting stack of m well layers and m+1 barrier layers, where at least five well layers have different energy band gaps, generating a broadband blue spectrum with a full width at half maximum (FWHM) of 30 nm or more and multiple peak inflection points, ensuring stability under varying current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a narrowband blue light-emitting diode is used to excite phosphor to generate white light, then the blue light intensity is high, but the spectrum waveform at the blue wavelength band becomes unstable when operating current changes
Solution Approach 1:
The light-emitting stack is divided into multiple quantum well layers (first to fifth well layers) with different energy band gaps, each generating light at different wavelengths. This segmentation creates a broadband blue spectrum with multiple peak inflection points, distributing the blue light intensity across multiple wavelengths rather than concentrating it at a single wavelength, thereby stabilizing the overall spectrum waveform when operating current changes.
Solution Approach 2:
The patent changes the energy band gap parameters of the well layers by varying the indium content in the InGaN material composition. The first to fifth well layers have progressively decreasing energy band gaps, creating a systematic parameter gradient that generates a broadband spectrum with controlled peak inflection points, improving spectrum stability under current variations.
2Power
If the operating current is varied to adjust light output, then the light intensity changes, but the spectrum waveform at the blue wavelength band fluctuates significantly
Solution Approach 1:
By segmenting the blue spectrum generation into five distinct quantum well layers with different energy band gaps, the patent creates multiple sub-peaks in the blue wavelength band. When operating current varies, these distributed peaks provide mutual compensation, maintaining overall spectrum waveform stability while allowing light output power to be adjusted.
Solution Approach 2:
The light-emitting stack uses composite InGaN quantum well structures with varying indium compositions to create a composite broadband blue spectrum. This composite approach combines multiple narrowband emissions from different well layers into a single stabilized broadband output that maintains spectral characteristics under varying current conditions.
3Device complexity
If a single well layer structure is used, then the device complexity is low, but the spectrum bandwidth is narrow and color rendering index varies with current
Solution Approach 1:
The light-emitting stack is segmented into five quantum well layers with progressively decreasing energy band gaps, creating a systematic structure that generates a broadband blue spectrum. This segmentation provides multiple peak inflection points that stabilize the spectrum waveform and maintain color rendering index stability across different operating current densities.
Solution Approach 2:
Each quantum well layer is designed with specific local properties (different indium content and energy band gaps) to generate light at specific wavelengths. The first well layer has the highest energy band gap and the fifth has the lowest, creating a local quality gradient that collectively produces a stabilized broadband spectrum with improved color rendering characteristics.
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 stabilizes the white light spectrum at the blue wavelength band and maintains high color rendering indices across different operating current densities, meeting industry standards.
Implementation Method 1
an epitaxial light-emitting structure to generate a light beam with a broadband blue spectrum
Implementation Method 2
The light-emitting stack includes m layers of well layers and m+1 layers of barrier layers, and the well layers and the barrier layers are alternately stacked. The well layers includes at least five well layers with different energy band gaps
Data Source
AI summary
A light-emitting module and a light-emitting diode are provided. The light-emitting diode includes an epitaxial light-emitting structure to generate a light beam with a broadband blue spectrum. A spectrum waveform of the broadband blue spectrum has a full width at half maximum (FWHM) larger than or equal to 30 nm. The spectrum waveform has a plurality of peak inflection points, and a difference between two wavelength values to which any two adjacent ones of the peak inflection points respectively correspond is less than or equal to 18 nm.