LED Asymmetric P-N Junction for Uniform Quantum Well Emission
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Solution Overview
Problem
Light-emitting diodes (LEDs) with multiple quantum wells suffer from non-uniform light emission and low internal quantum efficiency due to non-uniform distribution of charges, particularly holes, across different quantum wells, leading to limited radiative recombination and efficiency.
Innovation Solution
Incorporating an n-doped semiconductor buffer layer with a band gap energy less than or equal to 97% of the p-doped semiconductor layer creates asymmetry in the p-n junction, facilitating uniform carrier distribution across quantum wells, resulting in homogeneous light emission and improved internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple quantum wells are used in the LED structure, then light emission capability is improved, but internal quantum efficiency deteriorates due to non-uniform charge distribution
Solution Approach 1:
The patent introduces an asymmetric p-n junction structure where the n-type layer has a different doping concentration (10^18 to 10^20 atoms/cm³) compared to the p-type layer (10^18 to 10^20 atoms/cm³), creating an asymmetric charge distribution that promotes uniform hole injection across all quantum wells. This asymmetry resolves the non-uniform charge distribution problem while maintaining high light emission capability.
Solution Approach 2:
The patent optimizes the doping concentration parameters of the n-type and p-type layers, specifically setting the n-type doping concentration between 10^18 to 10^20 atoms/cm³ and p-type between 10^18 to 10^20 atoms/cm³. This parameter adjustment ensures uniform carrier distribution across multiple quantum wells, improving internal quantum efficiency while maintaining high light emission.
2Stability of the object's composition
If asymmetric doping concentrations are used in the p-n junction, then uniform charge distribution is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating regions with different doping concentrations - the n-type layer has doping concentration of 10^18 to 10^20 atoms/cm³ while the p-type layer has 10^18 to 10^20 atoms/cm³. This localized variation in doping quality achieves uniform charge distribution across quantum wells without requiring complex overall device architecture.
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 solution achieves a significant increase in internal quantum efficiency from 4% to 25% by ensuring uniform electron and hole distribution, enhancing light emission across all quantum wells and increasing current density.
Implementation Method 1
an n-doped semiconductor buffer layer located between the first layer and the active zone, the n-doped semiconductor in the buffer layer having a band gap energy less than or equal to about 97% of the band gap energy of the p-doped semiconductor in the second layer
Implementation Method 2
the radiative recombination ratio in the quantum wells is directly proportional to the product of the concentration of holes and electrons in the quantum wells
Implementation Method 3
at least two emissive layers comprising the semiconductor and capable of forming quantum wells
Data Source
AI summary
A light-emitting diode including: a first n-doped semiconductor layer configured to form a cathode, and a second p-doped semiconductor layer configured to form an anode, and together forming a p-n junction of the diode; an active zone located between the first layer and the second layer, including at least two emissive layers including a semiconductor capable of forming quantum wells, and a plurality of semiconductor barrier layers such that each emissive layer is located between two barrier layers; an n-doped semiconductor buffer layer located between the first layer and the active zone, the n-dope semiconductor of the buffer layer having a band gap energy less than or equal to about 97% of the band gap energy of the p-doped semiconductor of the second layer.