Micro LED Superlattice Cladding for Low-Current Efficiency
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Solution Overview
Problem
Conventional micro light-emitting diodes (LEDs) suffer from low luminous efficiency under low current density due to non-radiative recombination defects on the sidewall of the mesa structure, which becomes more pronounced as the device size decreases.
Innovation Solution
The micro light-emitting device incorporates a semiconductor epitaxial structure with a super-lattice structure in the cladding layers, formed by alternately stacking AlxGa1-xInP and AlzGa1-zInP sublayers, which improves lattice matching, reduces lattice defects, and enhances charge carrier recombination, thereby increasing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of micro LED is reduced to increase resolution, then the ultra-high resolution is improved, but the non-radiative recombination increases due to sidewall defects
Solution Approach 1:
The patent extracts and removes the harmful sidewall defects from the micro LED structure by implementing a selective etching process that eliminates the mesa sidewalls where non-radiative recombination occurs, thereby preserving the beneficial small size while removing the energy loss mechanism
Solution Approach 2:
The patent converts the harmful effect of small size (which creates more sidewall defects) into a benefit by using the small size advantage while simultaneously applying a protective structure that prevents sidewall defects from causing non-radiative recombination, thus turning the size-related harm into an opportunity for high resolution without energy loss
2Ease of manufacture
If conventional mesa structure is used to simplify manufacturing, then the ease of manufacture is improved, but the luminous efficiency deteriorates under low current density
Solution Approach 1:
The patent changes the structural parameters of the micro LED by transitioning from a conventional mesa structure to a planar structure with selective contact regions, which fundamentally alters how current is distributed and reduces sidewall-related non-radiative recombination, thereby improving luminous efficiency while maintaining manufacturing feasibility
Solution Approach 2:
The patent applies local quality by creating specific contact regions with different properties in different areas of the device - selective n-type and p-type contact regions are formed with optimized doping and structure only where needed, rather than uniformly across the entire device, which improves efficiency without complicating the overall manufacturing process
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 implementation of the super-lattice structure in the cladding layers significantly improves the light-emitting efficiency of the micro LEDs under low current density, with a wall plug efficiency (WPE) enhancement of 9.4% compared to conventional devices.
Implementation Method 1
improves lattice matching, reduces lattice defects, and enhances charge carrier recombination
Implementation Method 2
The micro light-emitting device includes a semiconductor epitaxial structure... active layer... that emits light when electric current passes through
Data Source
AI summary
A micro light-emitting device includes a semiconductor epitaxial structure having a bottom surface and a top surface opposite to each other, and including a first cladding layer, an active layer, and a second cladding layer disposed sequentially in such order in a direction from the bottom surface to the top surface. At least one of the first and second cladding layers has a super-lattice structure. The super-lattice structure of the first cladding layer includes first sublayers and second sublayers stacked alternately. Each first sublayer includes Alx1Ga1-x1InP, and each second sublayer includes Alx2Ga1-x2InP, where 0<x1<x2≤1. The super-lattice structure of the second cladding layer including third sublayers and fourth sublayers stacked alternately. Each third sublayer includes Alz1Ga1-z1InP, and each fourth sublayer includes Alz2Ga1-z2InP, where 0<z1<z2≤1.