UV-LED P-Type Doping Gradient for Higher Light Extraction
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Solution Overview
Problem
The challenge is to improve the luminous efficiency of ultraviolet Light Emitting Diodes (UV-LEDs) to enhance their disinfection efficiency in applications such as safe drinking water and daily sterilization.
Innovation Solution
A semiconductor structure for UV-LEDs is designed with a P-type semiconductor layer having a gradually decreasing P-type dopant concentration, an electron-hole compensation layer, and specific electrode materials to reduce charge carrier recombination and enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional P-type semiconductor layer structure is used, then manufacturing is simpler, but luminous efficiency is insufficient
Solution Approach 1:
The patent applies local quality by creating a P-type semiconductor layer with non-uniform dopant concentration distribution. The P-type dopant concentration gradually decreases from the first surface toward the second surface, creating different local properties within the same layer. This gradient structure optimizes carrier transport and light extraction efficiency in different regions, resolving the contradiction between manufacturing simplicity and luminous efficiency by introducing a controlled variation in material composition rather than a complete structural overhaul.
Solution Approach 2:
The patent implements parameter changes by modifying the dopant concentration parameter within the P-type semiconductor layer. Instead of using a uniform dopant concentration, the concentration is varied continuously or in steps from high at the first surface to low at the second surface. This parameter variation enables optimization of both electrical properties (carrier concentration, mobility) and optical properties (light extraction, waveguide mode suppression), thereby improving luminous efficiency without requiring fundamentally new device architecture.
2Productivity
If light extraction is not optimized, then device structure remains simple, but disinfection efficiency is limited
Solution Approach 1:
The gradient dopant concentration creates local variations in refractive index and carrier concentration that affect light propagation and extraction. Regions with different dopant concentrations contribute differently to light extraction efficiency, with the gradient structure helping to reduce total internal reflection and improve outcoupling of UV light, thereby reducing energy loss and enhancing disinfection efficiency.
Solution Approach 2:
By changing the dopant concentration parameter across the P-type layer, the patent modifies the optical properties of the semiconductor material. The varying carrier concentration affects the refractive index and absorption coefficient, enabling optimized light extraction across different depths of the device. This parameter optimization directly reduces energy loss from poor light extraction and improves the overall disinfection effectiveness.
3Duration of action of stationary object
If P-type dopant concentration is uniform, then manufacturing process is simpler, but luminous decay is faster
Solution Approach 1:
The non-uniform dopant concentration distribution creates different local environments for carrier recombination and defect formation. The gradient structure helps distribute stress and defects more evenly, reducing hot spots that would accelerate degradation. This local variation in material properties extends the operational lifespan by preventing uniform degradation patterns that occur in conventionally doped structures.
Solution Approach 2:
The patent uses parameter changes in dopant concentration to improve device reliability and lifespan. The gradual decrease in P-type dopant concentration from first to second surface creates a more stable electrical and optical field distribution, reducing stress concentrations and minimizing luminous decay over time. This parameter optimization addresses the contradiction by accepting increased manufacturing complexity in exchange for significantly extended device lifetime.
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 design significantly improves luminous efficiency and reduces luminous decay, enhancing the performance and reliability of UV-LEDs in disinfection applications.
Implementation Method 1
A P-type dopant concentration in the P-type contact layer gradually decreases along a direction from the first surface towards the second surface
Implementation Method 2
An ultraviolet Light Emitting Diode (UV-LED) is a solid-state semiconductor device capable of directly converting electrical energy into ultraviolet light
Data Source
AI summary
A light emitting diode includes a semiconductor structure, a first electrode, and a second electrode. The semiconductor structure has a first surface and a second surface. The semiconductor structure includes an N-type semiconductor layer, an active layer, and a P-type semiconductor layer that includes a P-type contact layer, and a P-type base layer located between the P-type contact layer and the active layer. The active layer is located between the N-type semiconductor layer and the P-type semiconductor layer. The first electrode is located on the second surface of the semiconductor structure, and is electrically connected to the N-type semiconductor layer. The second electrode is located on the second surface of the semiconductor structure, and is electrically connected to the P-type semiconductor layer. A P-type dopant concentration in the P-type contact layer gradually decreases along a direction from the first surface towards the second surface.