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The culprit of some GaN defects could be nitrogen

As silicon-based semiconductors reach their performance limits, gallium nitride (GaN) is becoming the next go-to material to advance light-emitting diode (LED) technologies, high-frequency transistors and photovoltaic devices. Holding GaN back, however, is its high numbers of defects.
This material degradation is due to dislocations—when atoms become displaced in the crystal lattice structure. When multiple dislocations simultaneously move from shear force, bonds along the lattice planes stretch and eventually break. As the atoms rearrange themselves to reform their bonds, some planes stay intact while others become permanently deformed, with only half planes in place. If the shear force is great enough, the dislocation will end up along the edge of the material.
Layering GaN on substrates of different materials makes the problem that much worse because the lattice structures typically don’t align. This is why expanding our understanding of how GaN defects form at the atomic level could improve the performance of the devices made using this material.
A team of researchers has taken a significant step toward this goal by examining and determining six core configurations of the GaN lattice. They presented their findings in the Journal of Applied Physics.

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#materials science #science #gallium nitride #defects #nitrogen #semiconductors #electronics #dislocations #edge dislocations #computational materials science

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Sun, 01 Jul 2018 09:20:28

Hey everybuddy! Today’s offering is another awesome guest post, this time by the lovely @911nmg, who’s been kind enough to share a story about chronic dislocations and joint weakness in the foot and ankle!
Dislocations are one of the most frequent injuries suffered by heroes in the action department, particularly in detective movies like the Lethal Weapon series. But the reality of living with loose joints and chronic dislocations is slightly less flashy than what we see on TV.
Remember that, because this is someone else’s life experience, I necessarily cannot verify everything that’s in the post, but it’s also very much not my place to censor what other people say about their own lives.
Thanks again to @911nmg for the gracious guest post and for being willing to share your story with us! Take it away!
xoxo, Aunt Scripty
[disclaimer]

Hi there!

I’ve been scrolling through the dislocation tag and found out not much has been asked about feet, so I wanted to give my story with it.

Since I was little I showed signs of having articular hypermobility, a benign alteration of the composition of muscles and tendons that allows for extra range of movements of the joints. I was thrilled with it because I wanted to be a dancer but it actually prevented me from becoming one.

At age 5 I had already had three shoulder dislocations (I wanted to cross the street without looking and my parents grabbed me so I wouldn’t get run over by a car, that was all it was needed for the joint to pop out) and a wrist one (fighting over a teddy bear) but one day in summer, running to get to beautifull purple flowers, both my right and my left foot popped out.

In the moment it wasn’t that bad, my dad put them back in place and I got two ankle bracelets, but over time it got worse, I kept on dislocating my right foot over and over, at school, in the park, on dance class, it was so common I actually learnt how to put it back on place myself.

At age ten however I was running on gym at school and I suddenly fell and I couldn’t get back up, my parents were informed and an ecography and scan later my doctor resolved I had scars on the peronean ligaments and I had to quit sports (just about a week after starting pointe shoe lessons).

Nevertheless it got worse and by age fifteen I was diagnosed with chronic pain, still I tried to live my life normally (do sports, wear high heels, go dancing all night) but at eighteen I was limping my way through life and I had to take pain killers everyday, so, I was put on intensive phisiotherapy.

We tried everything from thermo and criotherapy, passing through electric pulses, to good old fashioned masotherapy, I was given a lot of feet exercises to do, including balancing exercises with my bodyweight on a bosu balance trainer.

Today I’m 21, I have chronic pain but is manageable with ice, heat, exercises and the ocassional pain killer. All my shoes (including heels) are approved by my orthopedic doctor, I’m forbiden from doing high impact sports (so no step, or zumba, or running for me) and the occasional ones I do (skating and skiing) I strap myself with ankle braceles, ribon, and the closures of the boots so tight I have lost sensibility of my fingers more than once.

The worst thing for me is walking through irregular surfaces specialy sand, because it requires my feet to balance themselves over and over in the region of the ligament scars.

Hope this helps for all future writers out there.

Love your blog aunt scripty!

#submissions #dislocations #chronic illness #orthopedics #911nmg #submission