LED Semiconductor Doping for Efficiency Droop Reduction
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Solution Overview
Problem
Light Emitting Diodes (LEDs) experience efficiency droop at high current due to a disparity in electron and hole concentrations, primarily caused by the high ionization energy of acceptor atoms like Mg, leading to non-radiative recombination and reduced device efficiency.
Innovation Solution
Engineering the volumes of semiconductor regions in LEDs by adjusting the dopant concentrations and layer geometries, such as forming inverted pyramid or pyramid shapes, to achieve a more balanced electron and hole concentration within a specific percentage, thereby reducing efficiency droop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the n-type doping concentration is decreased to reduce electron concentration, then efficiency droop is reduced, but device resistance increases
Solution Approach 1:
The patent implements laterally selective doping where different regions of the n-type layer have different doping concentrations. The region under the MQW has lower doping to reduce electron concentration and efficiency droop, while other regions maintain higher doping to ensure adequate carrier supply and low resistance. This local differentiation resolves the contradiction by optimizing each region's doping level according to its specific functional requirements.
Solution Approach 2:
The n-type layer is segmented into multiple regions with different doping concentrations. Instead of using a uniform doping level throughout the entire layer, the patent divides it into zones: a first region with first doping concentration and a second region with second doping concentration. This segmentation allows independent optimization of electron concentration control versus resistance management in different spatial locations.
2Illumination intensity
If more LEDs are included to compensate for efficiency droop, then brightness is maintained, but device complexity increases
Solution Approach 1:
The patent changes the doping concentration parameter within the n-type layer to optimize LED performance. By adjusting the doping concentration laterally, the patent improves efficiency droop characteristics, allowing single LED operation at high brightness without requiring multiple LEDs in parallel. This parameter optimization maintains brightness while reducing device complexity.
3Loss of energy
If lateral doping is used to reduce electron concentration, then efficiency droop is minimized, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by implementing laterally selective doping where specific regions have optimized doping concentrations. This approach minimizes efficiency droop in critical areas while using standard doping processes in other regions, balancing performance improvement with manufacturing feasibility and cost control.
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
This approach enhances the operating efficiency of LEDs by minimizing efficiency droop and improving light extraction efficiency by ensuring a better match between electron and hole concentrations, reducing resistance and maintaining high brightness without increasing the number of LEDs or compromising device resistance.
Implementation Method 1
the oppositely charged free electrons and free holes recombine, producing light
Data Source
AI summary
A method or system for engineering at least one volume in a light emitting diode (LED) for higher operating efficiency includes forming a first semiconductor region of a light emitting diode doped with a first dopant concentration. A second semiconductor region of the light emitting diode doped with a second dopant concentration coupled to the first semiconductor region is formed. The forming the first semiconductor region or the forming the second semiconductor region further comprises forming a volume of the first semiconductor region or another volume of the second semiconductor region based on a calculation so that an electron concentration in the first semiconductor region or the second semiconductor region substantially matches within a first set percentage a hole concentration in the other one of the first semiconductor region or the second semiconductor region.