Ultraviolet Light Emitting Device With Graded AlGaN Layers
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Solution Overview
Problem
Current ultraviolet light emitting devices face challenges in achieving optimal electrical contact and transmittance due to high electrical contact resistance and defects in the semiconductor layers, which affect the internal quantum efficiency and reliability of the devices.
Innovation Solution
A light emitting device structure is developed with a first conductive semiconductor layer, an active layer, an electron blocking layer, a second conductive semiconductor layer with higher aluminum composition, and a third conductive semiconductor layer with lower aluminum composition for ohmic contact with the electrode, using AlGaN-based semiconductors to improve electrical contact resistance and transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a second conductive semiconductor layer with high aluminum composition is used, then the transmittance of ultraviolet light is improved, but the electrical contact resistance with the electrode increases
Solution Approach 1:
The semiconductor structure is divided into multiple conductive layers with different aluminum compositions. The second conductive semiconductor layer has higher aluminum composition for UV transmittance, while the third conductive semiconductor layer has lower aluminum composition for electrical contact, allowing each layer to optimize its specific function without compromise
Solution Approach 2:
Different regions of the semiconductor structure are assigned different material compositions tailored to local functional requirements. The upper region (second conductive layer) uses high aluminum content for optical performance, while the lower region (third conductive layer) uses low aluminum content for electrical performance, achieving spatial optimization of material properties
2Productivity
If the aluminum composition in the semiconductor layer is increased, then the ultraviolet light emission efficiency is improved, but the defects in the active layer increase
Solution Approach 1:
The semiconductor structure is segmented into multiple conductive layers with progressively decreasing aluminum compositions. This segmentation allows the active layer to be protected from defects by isolating it from high-aluminum layers that cause defects, while still maintaining high UV emission efficiency through the graded composition structure
Solution Approach 2:
The graded aluminum composition structure acts as a protective buffer between the high-aluminum regions (necessary for UV emission) and the active layer. This gradual transition prevents direct exposure of the active layer to defect-inducing high aluminum concentrations, cushioning against defect propagation before they can reach the active layer
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 solution enhances the electrical contact, transmittance, and internal quantum efficiency of the ultraviolet light emitting device, improving its reliability and performance for applications such as sterilization.
Implementation Method 1
the third conductive semiconductor layer has lower aluminum composition than that of the second conductive semiconductor layer and has an electrical contact resistance with the electrode that is lower than that of the second conductive semiconductor layer
Implementation Method 2
the second and third conductive semiconductor layers include an AlGaN semiconductor
Implementation Method 3
an active layer that is disposed on a first conductive semiconductor layer and generates ultraviolet wavelength
Data Source
AI summary
The present embodiments disclose a light emitting device.The light emitting device disclosed includes a first conductive semiconductor layer; an active layer that is disposed on a first conductive semiconductor layer and generates ultraviolet wavelength; an electron blocking layer that is disposed on the active layer; a second conductive semiconductor layer that is disposed on the electron blocking layer; a third conductive semiconductor layer that is disposed on the second conductive semiconductor layer; and an electrode that is disposed on the third conductive semiconductor layer, in which the second and third conductive semiconductor layers include an AlGaN semiconductor, and in which the third conductive semiconductor layer has a lower aluminum composition than that of the second conductive semiconductor layer and has an electrical contact resistance with the electrode that is lower than that of the second conductive semiconductor layer.