InGaN Quantum Well Chip with AlGaN Cladding for Low Current Efficiency
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Solution Overview
Problem
Existing optoelectronic semiconductor chips face challenges in achieving high efficiency at low current densities and maintaining stability at high temperatures, particularly in emitting light in the ultraviolet and visible spectral range.
Innovation Solution
An electrically pumped optoelectronic semiconductor chip with multiple radiation-active quantum wells made of InGaN, covered by AlGaN layers, where the charge carriers experience increased mobility and recombination due to band structure bending, enhancing efficiency and stability. The chip is designed with a specific structure that includes AlGaN cover layers, GaN intermediate layers, and a band gap configuration that favors hole conduction, optimizing quantum efficiency and reducing forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single quantum well structures are used, then device simplicity is maintained, but efficiency at low current densities is insufficient
Solution Approach 1:
The active region is segmented into multiple radiation-active quantum wells (at least two) instead of using a single quantum well structure. This segmentation allows each quantum well to contribute to light emission, with each generating at least 2.5% of total radiation, thereby significantly improving efficiency at low current densities while distributing the functional load across multiple units
Solution Approach 2:
Different quantum wells are positioned at different locations within the active region, with each quantum well having specific local properties optimized for radiation emission. The structure introduces local variations in composition (InGaN quantum wells with specific indium content) and positioning to enhance overall device performance at low current densities
2Illumination intensity
If high charge carrier density is used to increase brightness, then light emission intensity is improved, but efficiency at low current densities deteriorates
Solution Approach 1:
By dividing the active region into multiple quantum wells, the total radiation output is distributed across multiple emission sources. Each quantum well contributes at least 2.5% of total radiation, allowing the device to achieve high brightness through cumulative emission from multiple wells rather than requiring high charge carrier density in a single well, thereby maintaining high efficiency at low current densities
Solution Approach 2:
The invention changes the structural parameters by introducing multiple quantum wells with specific composition ranges (indium content 15-35%) and thickness parameters (2-10 nm). These parameter changes enable the device to achieve high brightness through increased number of emission centers rather than through high charge carrier density, resolving the contradiction between brightness and efficiency
3Reliability
If conventional cladding structures are used, then manufacturing simplicity is maintained, but quantum efficiency and stability at high temperatures are insufficient
Solution Approach 1:
The cladding structure uses composite AlGaN materials with varying aluminum content (20-70%) to create a multi-layered cladding system. This composite structure provides enhanced thermal stability and quantum efficiency through the specific band gap properties of AlGaN, while the gradual composition variation helps manage thermal stress and dislocation, improving high-temperature stability
Solution Approach 2:
The cladding structure is designed with local variations in aluminum content and layer thickness to optimize performance at different locations. The AlGaN cladding layers have specific local compositions (aluminum content 20-70%) tailored to provide appropriate band gap engineering and thermal management at each interface region, enhancing overall device stability at high temperatures
4Productivity
If multiple quantum wells are introduced to improve efficiency, then quantum efficiency is enhanced, but forward voltage increases
Solution Approach 1:
The invention optimizes parameters including quantum well thickness (2-10 nm), indium content (15-35%), and aluminum content in cladding layers (20-70%) to achieve high quantum efficiency. By carefully controlling these parameters, the device maintains reasonable forward voltage levels while achieving enhanced quantum efficiency through multiple radiation-active quantum wells contributing to 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 chip achieves increased internal and external quantum efficiency, improved brightness, and enhanced low-current and high-temperature stability, with reduced charge carrier density per quantum well, leading to efficient light emission at low current densities and elevated temperatures.
Implementation Method 1
During this propagation through the semiconductor chip, the charge carriers at least partially reach the radiation-active quantum wells, in which the positive charge carriers at least partially recombine with the negative charge carriers. The radiation emitted by the semiconductor chip is generated by means of this charge carrier recombination.
Implementation Method 2
the radiation-active quantum wells include or consist of InGaN... it contains at least two cover layers which include or consist of AlGaN... the charge carriers experience increased mobility and recombination due to band structure bending, enhancing efficiency and stability... a band gap configuration that favors hole conduction
Data Source
Figure 1A~2B
Figure 3~4B
AI summary
The invention relates to at least one embodiment of the electrically pumped optoelectronic semiconductor chip (1) comprising at least two radioactive quantum wells (2), wherein the radioactive quantum wells (2) comprise or are made of InGaN. The optoelectronic semiconductor chip (1) further comprises at least two coatings (4) comprising or made of AlGaN. Each of the coatings (4) is associated with exactly one of the radioactive quantum wells (2). The coatings (4) are each present at a p-side of the associated radioactive quantum well (2). A distance between the radioactive quantum well (2) and the associated coating (4) is no greater than 1.5 mm.