Why do GaN based LEDs continue to function despite a high number of defects?

In summary, GaN-based LEDs continue to function despite a high number of defects due to their robust material properties and the ability of the semiconductor structure to effectively manage and mitigate the effects of these defects. GaN's wide bandgap allows for efficient light emission, while the presence of defect-tolerant mechanisms enables the devices to maintain performance levels. Additionally, advancements in fabrication techniques and device engineering have improved the overall reliability and efficiency of GaN LEDs, allowing them to operate effectively even with inherent imperfections.
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TONGSU
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TL;DR Summary
Since the invention of GaN, Do we now understand why GaN based LED works given its huge number of defects?
From the book The Blue Laser Diode: The Complete Story, it said that

Indeed, maybe one of the most puzzling and amazing facts about present gallium nitride-based devices is why they work so well at all, given the huge numbers of defects in them!
I am wondering, after 20 years, is this problem still puzzling for scientists? How far have we understood about this problem?
 
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  • #2
TONGSU said:
TL;DR Summary: Since the invention of GaN, Do we now understand why GaN based LED works given its huge number of defects?

From the book The Blue Laser Diode: The Complete Story, it said thatI am wondering, after 20 years, is this problem still puzzling for scientists? How far have we understood about this problem?
Hi TONGSU

I am of the opinion that it is not that the lattice defects are not puzzling nor not understood, but that the problem is on how to overcome, or minimize, the lattice defects so that the operating lifetime of a device can be enhanced.

The book review
https://iopscience.iop.org/article/10.1088/0957-0233/12/6/703

Some discussion ( a difficult read unless immersed within the subject )
https://pubs.aip.org/aip/jap/articl...N-based-power-devices-Physics-reliability-and

https://onlinelibrary.wiley.com/doi/10.1002/pssa.202100727

https://www.sciencedaily.com/releases/2018/06/180629114705.htm
 
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  • #3
256bits said:
Hi TONGSU

I am of the opinion that it is not that the lattice defects are not puzzling nor not understood, but that the problem is on how to overcome, or minimize, the lattice defects so that the operating lifetime of a device can be enhanced.

The book review
https://iopscience.iop.org/article/10.1088/0957-0233/12/6/703

Some discussion ( a difficult read unless immersed within the subject )
https://pubs.aip.org/aip/jap/articl...N-based-power-devices-Physics-reliability-and

https://onlinelibrary.wiley.com/doi/10.1002/pssa.202100727

https://www.sciencedaily.com/releases/2018/06/180629114705.htm
I also noticed from the official website of UCSB about Gallium Nitride
UCSB Gallium Nitride that
"Generally, defects are bad for semiconductors, and they’re definitely bad for GaN, but it’s much more tolerant than other semiconductor, and we’re still trying to figure out why,” Speck said in 2017."
For the reason of why GaN is much more tolerant to defects, do we now have any conclusions?
 
  • #4
TONGSU said:
For the reason of why GaN is much more tolerant to defects, do we now have any conclusions?

My apologies for a late reply.
You would have to read up on research in the field to obtain more insight than I could provide.
 
  • #5
256bits said:
My apologies for a late reply.
You would have to read up on research in the field to obtain more insight than I could provide.
You could say something on this topic has already helped me a lot.
 
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You could try searching for Speck's name in Google scholar to see what papers he has published since 2017. The answer might be there. You could also try sending him an email.
 
  • #7
Haborix said:
You could try searching for Speck's name in Google scholar to see what papers he has published since 2017. The answer might be there. You could also try sending him an email.
I actually have sent him an email, but didn't get a reply.
 

FAQ: Why do GaN based LEDs continue to function despite a high number of defects?

1. What is GaN and why is it used in LEDs?

Gallium Nitride (GaN) is a semiconductor material known for its wide bandgap, which allows it to emit light efficiently in the blue and ultraviolet regions of the spectrum. Its properties make it ideal for high-performance light-emitting diodes (LEDs), particularly in applications requiring high brightness and efficiency, such as solid-state lighting and displays.

2. How do defects in GaN affect LED performance?

Defects in GaN can lead to non-radiative recombination, where electrons and holes recombine without emitting light, potentially reducing the efficiency of the LED. However, many of these defects do not significantly impact the overall performance because the majority of charge carriers can still recombine radiatively, allowing the LED to function effectively.

3. Why do GaN-based LEDs continue to operate despite defects?

GaN-based LEDs have a robust design that allows them to maintain functionality even with a considerable number of defects. The material's ability to support multiple pathways for charge carrier recombination and the presence of efficient radiative recombination processes help ensure that the LED can produce light effectively despite imperfections.

4. What role does the crystal structure of GaN play in its defect tolerance?

The wurtzite crystal structure of GaN is inherently more tolerant to defects compared to other semiconductor materials. This structure allows for better electronic and optical properties, enabling the material to sustain a higher density of defects while still performing efficiently, contributing to the longevity and reliability of GaN-based LEDs.

5. Are there any strategies to improve the performance of GaN-based LEDs in the presence of defects?

Yes, several strategies can be employed to enhance the performance of GaN-based LEDs despite defects. These include optimizing the growth conditions to minimize defects, using advanced techniques like quantum well structures to confine carriers and enhance radiative recombination, and incorporating post-growth treatments to repair or passivate defects, thereby improving overall efficiency and brightness.

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