High Barrier Layer in Multiple Quantum Well for LED Temperature Stability
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Solution Overview
Problem
Radiation-emitting optoelectronic semiconductor chips, such as LED and laser diode chips, experience a significant decrease in brightness with increasing temperature due to inefficient radiation generation, particularly in semiconductor materials like InGaAlP that emit in the 550 nm to 640 nm wavelength range.
Innovation Solution
Incorporating a high barrier layer with a larger electronic band gap into the multiple quantum well structure, positioned closer to the p-type semiconductor region, which acts as a charge carrier barrier, reducing hole dispersion and increasing radiation generation efficiency at higher temperatures by allowing more uniform charge carrier recombination across the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional multiple quantum well structure is used, then radiation generation efficiency is maintained at low temperatures, but brightness decreases significantly at high temperatures
Solution Approach 1:
The patent introduces a high barrier layer with a larger electronic band gap at a specific location within the multiple quantum well structure, closer to the p-type semiconductor region. This local modification creates a non-uniform barrier height distribution, where the high barrier layer selectively affects hole transport in its vicinity while other regions maintain their original barrier characteristics. This localized quality change enables preferential hole collection in specific quantum well layers, thereby reducing temperature dependence of brightness without compromising overall device performance
Solution Approach 2:
The patent changes the electronic band gap parameter of specific barrier layers by modifying their material composition. The high barrier layer is designed with a larger electronic band gap (Ehb) compared to the other barrier layers (Eb), creating a parameter differentiation within the structure. This parameter change alters the charge carrier transport characteristics, enabling the high barrier layer to act as a selective barrier that reduces hole dispersion at high temperatures, thus stabilizing brightness against temperature variations
2Reliability
If a high barrier layer is introduced to reduce temperature dependence, then brightness stability at high temperatures improves, but radiation generation efficiency decreases at low temperatures
Solution Approach 1:
The high barrier layer is positioned closer to the p-type semiconductor region rather than being uniformly distributed throughout the structure. This localized placement ensures that the strong hole-blocking effect is concentrated in a specific region, preventing excessive hole dispersion while still allowing sufficient hole injection and collection in the quantum well layers. The local quality modification thus achieves temperature stability without completely suppressing radiation generation efficiency at low temperatures
Solution Approach 2:
The patent employs a partial action approach by introducing only one or a few high barrier layers within the multiple quantum well structure, rather than making all barrier layers have high barrier characteristics. This partial implementation is sufficient to achieve the desired temperature stability effect while minimizing the negative impact on low-temperature radiation generation efficiency. The excessive action of making all barriers high would be unnecessary and would overly suppress carrier transport
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 design reduces the temperature dependence of radiation emission efficiency, compensating for the typical decline in brightness at higher temperatures and improving the temperature stability of the emitted radiation, while accepting a minor decrease in efficiency at lower temperatures.
Implementation Method 1
A high barrier layer is to be understood here and hereinbelow as being a barrier layer that has an electronic band gap Ehb which is larger than an electronic band gap Eb of the other barrier layers of the multiple quantum well structure
Implementation Method 2
the efficiency of radiation generation declines particularly at low temperatures
Data Source
AI summary
An optoelectronic semiconductor chip including a multi-quantum well including at least one high barrier layer is disclosed. In an embodiment, the chip includes a p-type semiconductor region, an n-type semiconductor region and an active layer suitable for emission of radiation arranged between the p-type region and the n-type region, wherein the active layer is in the form of a multiple quantum well structure. The multiple quantum well structure has a plurality of alternating quantum well layers and barrier layers, wherein a barrier layer arranged closer to the p-type region than to the n-type region is a high barrier layer having an electronic band gap Ehb that is larger than electronic band gaps Eb of other barrier layers, and wherein a quantum well layer that adjoins the high barrier layer on a side facing towards the p-type region has a thickness that is greater than thicknesses of other quantum well layers.