Near UV Light Emitting Device Electron Control Layer
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Solution Overview
Problem
Near ultraviolet light emitting devices face challenges in achieving high light output and extraction efficiency due to light absorption and inferior crystallinity, primarily because of the difficulty in growing thick AlGaN barrier layers with good crystallinity, which affects the electric and optical characteristics and increases the device's price compared to blue/green light emitting devices.
Innovation Solution
The implementation of a light emitting device structure with an n-type and p-type contact layer comprising AlGaN or AlInGaN, an active area with a multi-quantum well structure, and electron control layers to obstruct electron flow and enhance recombination rates, along with a first barrier layer containing a higher Al content than other barrier layers to delay electron flow and improve crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If AlGaN barrier layers are made thicker to improve light extraction efficiency, then light absorption is reduced, but crystallinity deteriorates and device performance decreases
Solution Approach 1:
The patent changes the compositional parameters of the barrier layer by introducing AlInGaN with varying Al and In content ratios. By optimizing the specific composition (e.g., Al0.2In0.1Ga0.7N), the patent achieves both thick layer growth with good crystallinity and reduced light absorption, resolving the contradiction between layer thickness and crystallinity quality
Solution Approach 2:
The patent uses composite AlInGaN material combining Al, In, and Ga elements in specific ratios. This composite approach allows tuning of both optical properties (reducing light absorption) and structural properties (maintaining crystallinity), enabling thick barrier layers without sacrificing material quality
2Loss of energy
If AlGaN contact layers are used to reduce light absorption, then light extraction efficiency improves, but device cost increases compared to blue/green LEDs
Solution Approach 1:
The patent optimizes the Al content parameter in AlGaN contact layers to achieve the minimum necessary thickness and composition that provides sufficient light extraction improvement while controlling material cost. By precisely controlling Al content rather than using high-Al compositions, the patent reduces material expense while maintaining energy efficiency benefits
Solution Approach 2:
The patent applies AlGaN or AlInGaN materials selectively in specific regions where light extraction is most critical (contact layers and barrier layers near the active region), rather than throughout the entire device structure. This localized application of premium materials reduces overall manufacturing cost while achieving the desired reduction in light absorption loss
3Illumination intensity
If electron blocking layers are added to improve light output, then recombination rate increases, but device structure becomes more complex
Solution Approach 1:
The patent designs barrier layers with dual functionality: they serve as both structural barriers for carrier confinement and as electron blocking layers to enhance recombination. By making the barrier layer perform multiple functions simultaneously, the patent improves light output without adding separate electron blocking layers, thus avoiding increased structural complexity
Solution Approach 2:
The patent merges the electron blocking function into the existing barrier layer structure by optimizing its composition and positioning. Instead of adding a separate electron blocking layer, the barrier layer is engineered to provide both carrier confinement and electron blocking, reducing the total number of layers while achieving improved recombination and light output
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 configuration improves light output and extraction efficiency by reducing light absorption and enhancing crystallinity, leading to increased recombination rates and improved operational characteristics at lower drive voltage.
Implementation Method 1
at least one electron control layer disposed between the n-type contact layer and the active area... to obstruct electron flow and enhance recombination rates
Implementation Method 2
a first barrier layer disposed nearest the n-type contact layer may contain a larger amount of Al than other barrier layers to delay electron flow and improve crystallinity
Implementation Method 3
a light emitting device including an InGaN well layer can be used to emit near ultraviolet light at wavelengths of 365 nm or greater
Implementation Method 4
light absorption occurs due to the semiconductor layers... significant light loss occurs
Data Source
AI summary
Disclosed is a near UV light emitting device. The light emitting device includes an n-type contact layer, a p-type contact layer, an active area of a multi-quantum well structure disposed between the n-type contact layer and the p-type contact layer, and at least one electron control layer disposed between the n-type contact layer and the active area. Each of the n-type contact layer and the p-type contact layer includes an AlInGaN or AlGaN layer, and the electron control layer is formed of AlInGaN or AlGaN. In addition, the electron control layer contains a larger amount of Al than adjacent layers to obstruct flow of electrons moving into the active area. Accordingly, electron mobility is deteriorated, thereby improving recombination rate of electrons and holes in the active area.