Mikael Björk | Hexagem: What crystallographic orientation offers superior hole confinement and indium composition control for high-performance InGaN quantum wells?
05:02 - 07:36
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What crystallographic orientation offers superior hole confinement and indium composition control for high-performance InGaN quantum wells?
Our MicroLED devices are engineered with the quantum well (QW) grown on the C-plane within the platelet structure, a deliberate choice based on its superior material properties. Theoretical studies indicate that the C-plane offers the largest hole confinement potential among all crystalline directions in InGaN, directly contributing to higher internal quantum efficiency (IQE). This orientation also provides enhanced control over indium composition uniformity across the quantum well, a critical factor for consistent emission wavelength and spectral purity, particularly when compared to the challenges of maintaining uniformity on S-plane facets where indium composition can vary significantly at facet intersections.
Cathodoluminescence spectroscopy confirms the high material quality and uniformity achieved with this C-plane growth approach. False-colored images reveal consistent red emission, typically around 650-660 nanometers, originating from the quantum well across individual platelets. Spectroscopic analysis demonstrates a narrow full width at half maximum (FWHM) of approximately 50 nanometers for individual spot measurements, with a platelet average of about 54 nanometers, indicating excellent compositional homogeneity and minimal spectral broadening.
In this short video, you can learn:
* The benefits of C-plane quantum well growth for hole confinement and IQE.
* How C-plane orientation improves indium composition uniformity in InGaN.
* The use of cathodoluminescence spectroscopy to characterize emission uniformity.
* The significance of narrow FWHM values for MicroLED spectral quality.
#CPlaneInGaN, #HoleConfinement, #IndiumCompositionControl, #QWUniformity, #MicroLED, #GaNTechnology
This is a highlight of the presentation:
A Bottom-Up InGaN Technology for Ultra-High Brightness MicroLED Displays
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01:28 - 02:46
Why does scaling MicroLEDs below 10 microns inherently compromise their efficiency, particularly for red emission?
Why does scaling MicroLEDs below 10 microns inherently compromise their efficiency, particularly for red emission?
The primary challenge in scaling MicroLEDs, especially for red emission, stems from fundamental material limitations and processing techniques. Red MicroLEDs require higher indium content in indium gallium nitride (InGaN) quantum wells, which exacerbates the lattice mismatch with the gallium nitride (GaN) buffer. This mismatch leads to the formation of dislocations and other defects, significantly degrading material quality and internal quantum efficiency. Furthermore, conventional planar LED fabrication relies on plasma processing, which induces surface and bulk material damage that becomes more pronounced as the device dimensions shrink and the surface-to-volume ratio increases.
In planar growth, achieving high material quality often necessitates thick GaN buffers, which introduce significant strain between the buffer and the underlying silicon or sapphire substrate. This strain, coupled with the thermal expansion mismatch between the layers and the wafer, can lead to substantial wafer bow. Such bowing complicates subsequent processing steps and can severely reduce manufacturing yield, posing a critical hurdle for large-scale production of high-performance MicroLED displays.
In this short video, you can learn:
* The impact of lattice mismatch on red InGaN quantum well quality.
* How plasma processing damages MicroLED materials, especially at smaller scales.
* The role of thick GaN buffers and thermal expansion mismatch in wafer bow.
* The challenges these issues pose for MicroLED efficiency and manufacturing yield.
#RedMicroLEDs, #InGaNQuantumWells, #LatticeMismatch, #PlasmaProcessingDamage, #MicroLED, #MicroLEDManufacturing
03:02 - 04:25
Can a non-planar, bottom-up growth approach fundamentally eliminate critical defects in GaN MicroLEDs?
Can a non-planar, bottom-up growth approach fundamentally eliminate critical defects in GaN MicroLEDs?
Our innovative approach employs a bottom-up, non-planar growth methodology to circumvent the inherent limitations of traditional MicroLED fabrication. We utilize conventional metal-organic chemical vapor deposition (MOCVD) to selectively grow indium gallium nitride (InGaN) in small, patterned openings (100-200 nanometers) within a silicon nitride growth mask on a gallium nitride (GaN) buffer. Crucially, these minute openings act as a dislocation filter, preventing defects from the underlying buffer layer from propagating into the actively grown platelet structures, thereby yielding dislocation-free material.
The resulting structures are truncated pyramids, or platelets, each forming a complete, functional LED. This selective growth process facilitates efficient strain relaxation due to the minimal interface area between the platelet and the buffer, enabling the direct growth of high-indium-content InGaN for red emission without inducing dislocations. Furthermore, this method eliminates the need for plasma processing, mitigating associated material damage, and prevents the formation of a continuous film, which avoids adding extra strain or exacerbating wafer bow issues.
In this short video, you can learn:
* The principles of bottom-up, non-planar GaN platelet growth.
* How small growth mask openings filter dislocations from the buffer layer.
* The mechanism for efficient strain relaxation in platelet structures.
* The advantages of avoiding plasma processing and film formation for MicroLED quality.
#BottomUpGrowth, #MOCVD, #DislocationFiltering, #GaNPlatelets, #MicroLEDs, #IIINitride