InGaN LED with Graded Quantum Wells for Homogeneous White Light
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Solution Overview
Problem
Current LED technologies producing white light with multiple quantum wells face challenges in achieving homogeneous light intensity across different wavelength ranges, leading to complexity and cost in manufacturing, as well as difficulty in adjusting the emitted color spectrum.
Innovation Solution
A light-emitting diode (LED) design featuring multiple quantum wells with varying indium compositions in emissive and barrier layers, allowing for homogeneous light intensity and adjustable color emission by controlling the indium compositions and power supply parameters, such as peak value and duty cycle of the periodic signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple p-n junctions are stacked to produce white light with different colors, then the color range and luminous intensity are improved, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges multiple quantum wells with different indium compositions into a single p-n junction structure. The active region contains multiple quantum wells (first, second, and third quantum wells) with progressively decreasing indium compositions, allowing all color emissions (red, green, blue) to occur within one junction rather than requiring three separate stacked junctions. This reduces device complexity while maintaining full color range capability.
Solution Approach 2:
A single p-n junction is designed to perform multiple functions by incorporating quantum wells with different indium compositions that emit at different wavelengths. The same junction structure produces red, green, and blue light simultaneously, making one component universal for full-color display applications rather than requiring specialized junctions for each color.
2Adaptability or versatility
If multiple p-n junctions are stacked to produce white light with different colors, then the color range and luminous intensity are improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges multiple quantum wells with different indium compositions into a single p-n junction structure. The active region contains multiple quantum wells (first, second, and third quantum wells) with progressively decreasing indium compositions, allowing all color emissions (red, green, blue) to occur within one junction rather than requiring three separate stacked junctions. This reduces device complexity while maintaining full color range capability.
3Adaptability or versatility
If quantum wells with different indium compositions are used to emit different wavelengths, then the color adjustability is improved, but the light intensity homogeneity deteriorates
Solution Approach 1:
The patent applies local quality by giving each quantum well a specific indium composition tailored to its emission wavelength function. The first quantum well has higher indium composition for red emission, the second has intermediate composition for green, and the third has lower composition for blue. This localized compositional variation optimizes each region's light emission characteristics while maintaining overall intensity balance through the graded structure.
Solution Approach 2:
The patent systematically changes the indium composition parameter across different quantum wells to achieve different emission wavelengths. By progressively decreasing the indium composition from the first to the third quantum well, the patent adjusts the bandgap energy to emit red, green, and blue light respectively, while the graded composition profile helps maintain homogeneous light intensity across all wavelengths.
4Use of energy by moving object
If GaN-based materials with high forbidden band energy are used, then UV and blue light emission is achieved, but the wavelength adjustment range is limited
Solution Approach 1:
The patent changes the compositional parameter of the GaN-based material by incorporating indium to form InGaN alloys with varying indium compositions. This parameter change reduces the forbidden band energy from pure GaN (3.42 eV for UV) to InGaN with lower bandgap, enabling wavelength extension from UV through blue to green and red regions. The progressive indium composition variation across quantum wells achieves broad wavelength coverage while maintaining efficient light emission.
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 LED achieves homogeneous light emission across different wavelength ranges, enabling easy adjustment of the color spectrum from red to blue to white, with reduced threshold voltage and improved manufacturing efficiency.
Implementation Method 1
By passing an electric current through this structure, radiative recombinations of charges (electrons and holes) are then obtained at the level of the depletion zone, resulting in light emission from the quantum wells
Implementation Method 2
A depletion zone is then obtained at the level of the junction, and in particular at the level of the quantum wells
Data Source
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AI summary
The invention relates to a light-emitting device comprising a light-emitting diode (100) having a layer of n-doped InGaN (102) and a layer of p-doped GaN (104), and an active zone (110) comprising a number m of InGaN-emitting layers (112), each disposed between two InGaN barrier layers (114), in which the indium compositions of the emitting layers are different and greater on the side of the n-doped InGaN layer than on the side of the p-doped GaN layer, and the indium compositions of the barrier layers are different and greater on the side of the n-doped InGaN layer than on the side of the p-doped GaN layer, as well as comprising: an electric power supply for supplying the diode with a periodic signal; and a device for controlling the power supply, which can alter the peak value of the periodic signal according to a spectrum of the emitted light.