Multicolor Nanowire LED Integration for Uniform Wavelength Control
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Solution Overview
Problem
The integration of mini-LEDs and micro-LEDs faces challenges in achieving efficient multicolor emission with high uniformity and stability due to limitations in top-down etching processes, low yield of defect-free mass transfer, and inefficiencies in deep-visible spectrum operation using conventional InGaN quantum wells.
Innovation Solution
Monolithic integration of multicolor LEDs with highly spatially uniform emission wavelengths is achieved through selective area epitaxy, where the indium content and emission colors are precisely controlled by adjusting the nanowire emitter diameter and lattice constant, resulting in narrow spectral linewidths and directional emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If top-down etching is used for processing micro-LEDs, then micro-LED devices can be manufactured, but the external quantum efficiency is limited to around ten percent
Solution Approach 1:
The patent inverts the conventional top-down etching approach by using bottom-up nanowire growth to form micro-LEDs. Instead of etching away material to create LED structures, the invention grows nanowires directly into the desired configuration, thereby avoiding the efficiency degradation caused by top-down processing while maintaining manufacturability
Solution Approach 2:
The patent changes the fundamental processing parameter from etching (removal) to epitaxial growth (addition). This parameter change enables the nanowire-based micro-LED structure to achieve superior external quantum efficiency compared to conventional top-down etched devices
2Adaptability or versatility
If nanowire diameter and lattice constant are adjusted to tune emission colors, then multicolor emission can be achieved, but variations in nanowire size may impact photonic crystal bandgap and InGaN LED active region bandgap
Solution Approach 1:
The patent applies local quality by allowing different nanowire regions to have different diameters and lattice constants tailored to specific emission color requirements. Each nanowire can be locally optimized for its intended wavelength while the overall array maintains uniformity through controlled growth conditions
Solution Approach 2:
The patent implements feedback control during the selective area epitaxy process to monitor and adjust nanowire growth parameters. This ensures that nanowire diameter and lattice constant variations remain within tight tolerances, maintaining emission wavelength uniformity across the array while enabling multicolor tuning
3Ease of manufacture
If conventional InGaN quantum wells are used for deep-visible spectrum LEDs, then LED operation can be achieved, but high efficiency operation remains challenging
Solution Approach 1:
The patent uses composite material structures combining nanowire-based InGaN active regions with photonic crystal structures. This composite approach enables efficient deep-visible spectrum emission by combining the electrical properties of InGaN with the optical enhancement of photonic crystals, overcoming the efficiency limitations of conventional InGaN quantum wells
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 enables the simultaneous achievement of ultra-stable operation, ultra-narrow linewidth, and highly directional emission in multicolor LED arrays, enhancing the efficiency and uniformity of micro-LED displays with current densities exceeding 1000 A/cm² at 10 volts.
Implementation Method 1
monolithic integration of multicolor LEDs with highly spatially uniform emission wavelengths are realized in a single selective area epitaxy process
Implementation Method 2
an array of photonic bandgap LEDs disposed on the substrate. The array includes photonic bandgap LEDs operable for emitting different colors of light
Implementation Method 3
monolithic integration of multicolor LEDs with highly spatially uniform emission wavelengths are realized in a single selective area epitaxy process
Data Source
AI summary
Monolithic integration of multicolor light-emitting diodes with highly spatially uniform emission wavelength are realized in a single selective area epitaxy process. Pronounced emission peaks with very narrow spectral linewidths are also achieved. The indium contents and emission colors are tuned by precisely controlling the nanowire emitter diameter and lattice constant. The emission wavelengths exhibit small variations of only a few nanometers among individual nanowire emitters over an areal region.