SPSL Semiconductor Layer for LED Light Transmission and Conduction
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Solution Overview
Problem
Semiconductor light emitting devices, such as LEDs, face inefficiencies due to compositional and doping inhomogeneities in semiconductor layers, leading to variations in refractive index and band gap energy, which affect light absorption and conduction properties.
Innovation Solution
A short period superlattice (SPSL) semiconductor layer is designed with alternating barriers and wells, where transparent regions with high transmission coefficients and higher conductive regions are optimized to balance light transmission and current flow, reducing voltage drop and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compositional inhomogeneities are present in semiconductor layers, then carrier localization and conduction are improved, but light absorption increases reducing transmission efficiency
Solution Approach 1:
The semiconductor layer is segmented into multiple quantum wells separated by barriers, creating distinct regions with different functions. The quantum wells provide carrier localization and conduction pathways, while the barriers provide transparent regions for light transmission. This segmentation allows the layer to simultaneously achieve good conduction through the wells and low light absorption through the barriers.
Solution Approach 2:
Different regions of the semiconductor layer are given different compositions and properties. The quantum wells have compositions optimized for carrier confinement and conduction, while the barriers have compositions optimized for optical transparency. This local differentiation of properties allows simultaneous optimization of both conduction and light transmission without compromise.
2Loss of energy
If uniform composition is used in semiconductor layers, then light transmission is improved, but carrier conduction and localization are reduced
Solution Approach 1:
Rather than using a uniform composition, the layer is divided into repeating units of quantum wells and barriers. This segmentation creates localized regions of high carrier concentration in the wells for effective conduction, while the barriers maintain optical transparency. The periodic structure ensures both functions are achieved throughout the layer.
Solution Approach 2:
The semiconductor layer is constructed as a composite structure combining different alloy compositions (e.g., AlGaAs and GaAs, or InGaN and GaN) to form quantum wells and barriers. This composite approach allows each material to contribute its optimal properties: one material provides carrier confinement and conduction, while the other provides optical transparency.
3Illumination intensity
If aluminum content is increased in AlGaN layers, then band gap energy increases improving light emission, but compositional fluctuations increase causing inhomogeneities
Solution Approach 1:
The high-aluminum-content layer is segmented into quantum wells separated by barriers with different compositions. This segmentation allows the high-Al regions to provide the desired band gap for UV emission while the barriers provide compositional stability and reduce overall fluctuations. The periodic structure distributes the compositional stress.
Solution Approach 2:
The aluminum composition parameter is varied periodically through the layer thickness, creating alternating high-Al and low-Al regions. This parameter modulation allows the average band gap to be optimized for light emission while the periodic variation reduces cumulative compositional fluctuations and maintains structural stability.
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 SPSL structure improves light emission efficiency by minimizing light absorption and maintaining a low voltage drop, achieving higher conduction and transmission while optimizing the semiconductor material for light emitting applications.
Implementation Method 1
These compositional fluctuations, together with doping fluctuations, also known as localized inhomogeneities, result in carrier localization and lead to the creation of conduction layers for carriers.
Implementation Method 2
transparent regions with high transmission coefficients and higher conductive regions are optimized to balance light transmission and current flow, reducing voltage drop and enhancing efficiency
Implementation Method 3
Each semiconducting layer has a particular combination of molar fractions (e.g., x, y, and z) for the various elements, which influences the electronic and optical properties of the layer. In particular, the refractive index and absorption characteristics of a layer are sensitive to the molar fractions of the semiconductor alloy.
Data Source
AI summary
A device including one or more layers with lateral regions configured to facilitate the transmission of radiation through the layer and lateral regions configured to facilitate current flow through the layer is provided. The layer can comprise a short period superlattice, which includes barriers alternating with wells. In this case, the barriers can include both transparent regions, which are configured to reduce an amount of radiation that is absorbed in the layer, and higher conductive regions, which are configured to keep the voltage drop across the layer within a desired range.