UV LED Nano-Diamond Structure for Higher Light Extraction
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Solution Overview
Problem
The limited hole injection efficiency of the p-type AlGaN layer in ultraviolet LEDs results in poor ohmic contacts and low light extraction efficiency due to strong absorption of UV light by the p-GaN layer, leading to heat generation and reduced device reliability.
Innovation Solution
Incorporating a nano-diamond structure in the second semiconductor layer with a conductivity type matching that of the second semiconductor layer, which reduces UV light absorption and enhances light extraction efficiency through reflective properties and improved ohmic contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a p-GaN layer is used to make p-type ohmic contacts on the p-type layer to increase hole injection efficiency, then the hole injection efficiency is improved, but the light extraction efficiency deteriorates due to strong absorption of UV light by the p-GaN layer
Solution Approach 1:
The patent extracts the harmful p-GaN layer that absorbs UV light and replaces it with a p-type AlInGaN layer having lower absorption coefficient. This removal of the light-absorbing component directly resolves the contradiction by eliminating the root cause of light extraction loss while preserving the necessary electrical functionality through the alternative p-type layer design.
Solution Approach 2:
The patent changes the material composition parameter from p-GaN to p-type AlInGaN, which fundamentally alters the optical absorption characteristics. By adjusting the aluminum and indium content in the AlInGaN layer, the absorption coefficient is reduced while maintaining adequate hole injection capability, thus resolving the trade-off between electrical and optical performance.
2Reliability
If a p-GaN layer is used to make p-type ohmic contacts, then good ohmic contact is achieved, but the device temperature rises due to heat generation from absorbed light
Solution Approach 1:
The patent removes the heat-generating p-GaN layer and substitutes it with p-type AlInGaN that has reduced light absorption. This extraction of the harmful element eliminates the primary heat source while maintaining the necessary electrical contact quality, directly addressing the temperature rise problem.
Solution Approach 2:
The patent employs a composite semiconductor structure where p-type AlInGaN is integrated with the AlGaN-based quantum well layers. This composite material approach allows optimization of both electrical contact properties and optical transparency, reducing heat generation while maintaining device functionality.
3Reliability
If the p-type layer strongly absorbs UV light to enable hole injection, then charge carrier injection is improved, but the light emission from quantum well cannot be extracted
Solution Approach 1:
The patent modifies the material composition parameters by introducing aluminum and indium into the p-type layer to create AlInGaN. This parameter change reduces the bandgap and absorption coefficient in the UV range, allowing light emission to pass through while maintaining adequate charge carrier injection through appropriate doping and composition optimization.
Solution Approach 2:
The patent applies different material compositions at different locations: the p-type AlInGaN layer near the contact region maintains higher aluminum content for good ohmic contact, while the region closer to the quantum well has optimized composition for minimal absorption. This spatial variation in material quality resolves the contradiction between injection and extraction requirements.
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 nano-diamond structure effectively minimizes UV light absorption, increases light extraction efficiency, and improves device brightness by reflecting UV light, thereby enhancing the reliability of the optoelectronic device.
Implementation Method 1
the light radiated from the quantum well to the p-type layer is absorbed by the p-GaN layer and cannot be extracted... the nano-diamond structure... enhances light extraction efficiency through reflective properties
Data Source
AI summary
Disclosed are an optoelectronic device and a preparation method thereof. The optoelectronic device includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence. The conductivity type of the first semiconductor layer is opposite to that of the second semiconductor layer, and the second semiconductor layer is provided with a layer of nano-diamond structure, and the nano-diamond structure has the same conductivity type as the second semiconductor layer. The method for preparing the optoelectronic device is used to make the optoelectronic device. In the present application, by providing a layer of nano-diamond structure in the second semiconductor layer, the absorption of UV light emitted by the active layer can be effectively avoided, and the beneficial effect of greatly improving the light extraction efficiency of the UV LED can be achieved.