Deep UV Light-Emitting Device with Vertical Protrusion Reflection
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Solution Overview
Problem
Deep ultraviolet light-emitting diodes made of aluminum indium gallium nitride (AlInGaN) suffer from reduced luminous efficiency due to light absorption in the epitaxial layer during lateral propagation, as the aluminum concentration is high, leading to inefficient light emission.
Innovation Solution
A light-emitting device structure comprising a substrate, a first type semiconductor layer (AlxGa1-xN), a protrusion with an active layer, and a first reflection structure that penetrates through the semiconductor layers, reducing light absorption by shortening the propagation path and enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If aluminum concentration in AlInGaN is increased to form the epitaxial layer of deep ultraviolet light-emitting diode, then the emission wavelength can be reduced to deep ultraviolet range, but light is absorbed by the epitaxial layer during lateral propagation, reducing luminous efficiency
Solution Approach 1:
The patent introduces a vertical dimension to light propagation by creating a protrusion structure with a reflection structure at its bottom. This transforms the conventional lateral light propagation path into a vertical emission path, allowing light to escape through the top surface of the protrusion rather than propagating laterally through the absorbing epitaxial layer. This dimensional change resolves the contradiction by enabling deep ultraviolet emission while avoiding absorption losses.
Solution Approach 2:
The patent segments the light-emitting structure into distinct functional regions: the protrusion structure for light generation and escape, and the surrounding epitaxial layer for electrical function. The reflection structure at the bottom of the protrusion further segments the light path, reflecting upward-propagating light toward the emission surface. This segmentation allows optimized light extraction without compromising the overall device performance.
2Device complexity
If light propagates laterally through the epitaxial layer, then the device structure can be simplified, but light absorption by the epitaxial layer prevents efficient light emission
Solution Approach 1:
By introducing the protrusion structure with vertical light emission capability, the patent adds structural complexity in exchange for dramatically improved light extraction efficiency. The vertical emission path through the protrusion top surface eliminates the need for complex lateral light guiding structures, as the protrusion itself serves as both the light-generating and light-escaping region.
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 device effectively reduces light absorption by the semiconductor layer, thereby improving the luminous efficiency of deep ultraviolet light-emitting diodes by optimizing the light propagation path and emission wavelength range from 200 nm to 320 nm.
Implementation Method 1
A first reflection structure is disposed in the protrusion, and penetrates through the second type semiconductor layer, the active layer of the protrusion and into the first type semiconductor layer
Data Source
AI summary
A light-emitting device includes a substrate, a first type semiconductor layer, a protrusion, and a first reflection structure. The first type semiconductor layer is disposed on a surface of the substrate, and has a surface that has first and second conductive regions. The first type semiconductor layer is made of AlxGa1-xN, and x ranges from 0 to 1. A protrusion includes an active layer and a second type semiconductor layer that are sequentially disposed on the first conductive region of the surface of the first type semiconductor layer in such order. A first reflection structure is disposed in the protrusion, and penetrates through the second type semiconductor layer, the active layer of the protrusion and into the first type semiconductor layer. The light-emitting device emits light that has an emission wavelength ranging from 200 nm to 320 nm.