LED Current Confinement via Resistivity Gradient
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in confining charge carriers efficiently, leading to suboptimal luminous efficiency due to uneven resistivity distribution in semiconductor layers.
Innovation Solution
A light-emitting diode design featuring a first type semiconductor layer with a high resistance portion that encloses low resistance portions, where the resistivity increases from the low resistance portion towards the high resistance portion, effectively confining charge carriers within the low resistance area, thereby preventing current flow between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional semiconductor layer with uniform resistivity is used, then the structure is simple, but charge carriers are not confined efficiently leading to suboptimal luminous efficiency
Solution Approach 1:
The semiconductor layer is designed with spatially varying resistivity, where different regions (first, second, and third portions) have different resistance characteristics. The first and second portions have lower resistivity to facilitate carrier injection, while the third portion has higher resistivity to confine carriers within the active region, preventing carrier leakage and improving luminous efficiency.
2Reliability
If the resistivity is increased to confine charge carriers, then luminous efficiency improves, but current flow between electrodes is blocked
Solution Approach 1:
Different regions of the semiconductor layer are assigned different resistivity values to perform different functions: the first and second portions have lower resistivity to allow current flow and carrier injection from electrodes, while the third portion positioned between them has higher resistivity to confine carriers laterally within the active region, thus achieving both current conduction and carrier confinement.
Solution Approach 2:
The third portion of the semiconductor layer with higher resistivity acts as an intermediary structure between the first and second portions. It serves as a lateral barrier that prevents carrier diffusion outside the active region while still allowing vertical current flow, thus mediating between the need for carrier confinement and current conduction.
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 configuration enhances the luminous efficiency of the LED by ensuring charge carriers flow through the low resistance portion, improving light emission performance.
Implementation Method 1
The first type semiconductor layer includes a first low resistance portion, at least one second low resistance portion, and a high resistance portion. The resistivity of the first type semiconductor layer increases from the first low resistance portion toward the high resistance portion and decreases from the high resistance portion toward the second low resistance portion. The high resistance portion is configured to confine charge carriers substantially within the first low resistance portion.
Data Source
AI summary
A light-emitting diode includes semiconductor layers and electrodes. A first type semiconductor layer includes first and second low resistance portions and a high resistance portion therebetween. The high resistance portion encloses the first low resistance portion and is configured to confine charge carriers substantially within the first low resistance portion. A resistivity of the first type semiconductor layer increases from the first low resistance portion toward the high resistance portion and decreases from the high resistance portion toward the second low resistance portion. A first electrode is electrically connected to the first low resistance portion and substantially no current flows between the first electrode and the second low resistance portion. A portion of the first type semiconductor layer is between the first electrode and a second type semiconductor layer. A second electrode is electrically connected to the second type semiconductor layer.