Thank you so much for sharing this talk with us. It really gives a great understanding of your work as a scientist. Seeing footage from January is like time travel though: Live audiences in indoor spaces, the speaker coughing in public and brushing it off, and of course that the impurity of semiconductor crystals was the most pressing concern in this room.
Yeah the pre-covid time capsule effect is pretty strong with this one... I noticed that too. At the time I was speaking here I was nearly over my second few-week cold - and still coughing onstage.
I always thought that 3-5 crystals made good semiconductors because having 4 valence electrons was an ideal neutral position between metal and nonmetal, hence silicon and germanium and such. And I think amorphous carbon has a negative tempco, and grey tin is also distinctly nonmetallic, so these also exhibit some semiconductor-like properties. Same for 2-6 semiconductors, silicon carbide, etc. So the existence of 4-6 semiconductors threw me off. Then again, I’ve heard about selenium rectifiers before. No surprise that my understanding of condensed matter isn’t what it could be, I barely passed that paper.
It's so interesting seeing "real" crystal science. I'd love to see you do a video addressing crystal pseudoscience one day, but I understand if you'd rather not touch such "controversial" topics.
@@AlphaPhoenixChannel Definitely makes sense. I'm a medical biologist and I don't engage with anti-vaxers and whatnot either. Thanks for all of the awesome videos! I appreciate the breadth of your interests from chemistry and physics to astronomy and computer science!
Sorry about that but I fear this is as good as it gets - the original recording was from a waterproof GoPro sitting in the first row and I spent literally a couple hours trying to deecho and denoise. Most of the weird noises now are artifacts of that process - coughs from the audience sent through a pile of filters. Unfortunately there’s still hiss at 8kHz that’s directly on top of my voice so I couldn’t notch it out.
@@AlphaPhoenixChannel Arguably, the benefit of recording a new voice track over the existing video would outweigh the effort, but that's not for me to decide. Thanks for the content either way!
@@AlphaPhoenixChannel The hiss exactly coincides with my tinnitus frequency and plays merry hell with it. :( I wonder if more advanced software, such as iZotope's RX 8 (30-day free trial), specifically designed to clean up this kind of recording might be worth investigating. Just a thought. Great talk, anyway!
@@AlphaPhoenixChannel Might have been better to just re-record the talk with your good mic and show the slides as the visuals + less time spent working on it + Slides are actually readable + excellent audio quality
really interesting talk. In the begining you mentioned that the "wetting" of your depositions was an issue. What this addressed or solved in your studies? I have similar interest in reducing surface tensions in solids to improve "wetting" during sintering.
Why aren't lecture Halls build more like auditoriums instead of echo chambers? I can deal with the noice (gain set too high, or it's sitting on the A/C duct) it's the multipath frequncy smear.
I've always had the fantasy of using survivalist accessible methods to make a computer. One of my ideas was to make the transistors with PbS (Galena) since you could practically get that out in the wild relatively easily. other than the fact that it would be (a) easy to get, and (b) a semiconductor.... I have no idea where one would go from there. I had assumed something like the germanium "cat whisker" junctions could be formed with the right dope-ant laced wires.
8μm? That’s thermal infrared! Sounds like that sort of tech might be replacing pyroelectric sensors in a decade or two! Though I couldn’t say whether it would be cheaper or more effective.
Very nice talk. The only thing that isn't clear to me is why you're growing PbSe on top of a III-V semiconductor - it seemed from the presentation that growing a IV-VI on a III-V is more difficult than on another IV-VI. Do we just not have means to manufacture a IV-VI substrate, so we're stuck with a III-V? Or do III-V have other nice properties that make it desirable to have a III-V below the PbSe?
Both! iii-v substrates are much cheaper, much more thermally conductive and have better mechanical strength and chemical stability than either native iv-vi substrates or the old fluorite substrates. You’re correct it WOULD be easier to do homoepi on pbse substrates but we never bothered to try because it wasn’t going to be useful. There are also buckets and buckets of institutional knowledge surrounding iii-vs so by working with them we could get a lot more help!
Very interesting stuff! You mention that the effects at the interface would be more important for quantum applications than conventional semiconductor stuff. Do these rely on different properties of the materials, or are they excited differently? Or do both rely on the same property, but the quantum use case is just less fault-tolerant?
There are loads of interfacial effects in semiconductors that all rely on slightly different physics. In this case the electronic structure in one material has different symmetry than the electronic structure in the other material. Because that symmetry is sort of a fundamental property of space that’s continuously varying everywhere, that means everything has to pinch shut between the two materials in order to flip from one symmetry to the other, leading to weird things that only happen literally AT an interface and nowhere else. The much more commonly studied “2D Electron Gas” exists at GaAs/AlGaAs interfaces and is the foundation of a lot of cool quantumy research although it’s not based on the topology/symmetry/weird stuff I was talking about here
@@AlphaPhoenixChannel Thanks! It's very interesting for me to think of the molecular-level interface and how it is created, as opposed to just assuming an instantaneous/perfect transition (to make the maths easier for field calculations etc.).
AH-HA!! It IS a semiconductor!! In your vid about the bean deposition I saw the sample and thought it looked like a CPU chip and left a comment rambling on about silicon semiconductors reaching their limit and then went on to photonic processors. But I was trying to figure out if you were making semiconductors and now I know you are.. neat-o! LOL :D
Pretty sure everyone in this audience had Covid after that... Also kind of interesting that apparently recording tech at all universities seems to be stuck in the 80ies.
That guy literally exploding his lungs while he coughs directly into the microphone at the beginning is my spirit animal
i cant stop laughing 😂
Haha, I was thinking the same thing, have another toke man lmao.
You're right, you did do a fantastic job making this talk approachable by people outside your field. Thanks for sharing.
Thank you so much for sharing this talk with us. It really gives a great understanding of your work as a scientist.
Seeing footage from January is like time travel though: Live audiences in indoor spaces, the speaker coughing in public and brushing it off, and of course that the impurity of semiconductor crystals was the most pressing concern in this room.
Yeah the pre-covid time capsule effect is pretty strong with this one... I noticed that too. At the time I was speaking here I was nearly over my second few-week cold - and still coughing onstage.
I am currently following courses on Solid State physics and it's great to see some real up-to-date physics on a very nice channel.
Glad you liked it!
I always thought that 3-5 crystals made good semiconductors because having 4 valence electrons was an ideal neutral position between metal and nonmetal, hence silicon and germanium and such. And I think amorphous carbon has a negative tempco, and grey tin is also distinctly nonmetallic, so these also exhibit some semiconductor-like properties. Same for 2-6 semiconductors, silicon carbide, etc. So the existence of 4-6 semiconductors threw me off. Then again, I’ve heard about selenium rectifiers before. No surprise that my understanding of condensed matter isn’t what it could be, I barely passed that paper.
Nice!
And perfect timing: I was literally showing your channels to my students a couple of hours ago! 🤣
Presentation was fine, but possibly run the audio through some processing to clean it up a bit? it was a bit harsh.
Hey man, can you inspect guage blocks under a electron microscope, recently saw Steve mould n others play with it.
It's so interesting seeing "real" crystal science. I'd love to see you do a video addressing crystal pseudoscience one day, but I understand if you'd rather not touch such "controversial" topics.
Engaging with the crap only lends it credence. I periodically scrub the sarcastic comments making fun of flat earthers on my astro timelapses.
@@AlphaPhoenixChannel Definitely makes sense. I'm a medical biologist and I don't engage with anti-vaxers and whatnot either. Thanks for all of the awesome videos! I appreciate the breadth of your interests from chemistry and physics to astronomy and computer science!
You channel is like a pearl!
Any chance of cleaning up the audio or recording a new track? It's nice content, but I gave up after 2/3 on mobile.
Sorry about that but I fear this is as good as it gets - the original recording was from a waterproof GoPro sitting in the first row and I spent literally a couple hours trying to deecho and denoise. Most of the weird noises now are artifacts of that process - coughs from the audience sent through a pile of filters. Unfortunately there’s still hiss at 8kHz that’s directly on top of my voice so I couldn’t notch it out.
@@AlphaPhoenixChannel Arguably, the benefit of recording a new voice track over the existing video would outweigh the effort, but that's not for me to decide.
Thanks for the content either way!
@@AlphaPhoenixChannel The hiss exactly coincides with my tinnitus frequency and plays merry hell with it. :( I wonder if more advanced software, such as iZotope's RX 8 (30-day free trial), specifically designed to clean up this kind of recording might be worth investigating. Just a thought. Great talk, anyway!
@@AlphaPhoenixChannel Might have been better to just re-record the talk with your good mic and show the slides as the visuals
+ less time spent working on it
+ Slides are actually readable
+ excellent audio quality
Just watched you make your play button, it's good to learn more about the subject after seeing it in action. keep it up you'll be at the next one soon
Amazing and absolutely fascinating
new subscriber here! please keep the videos coming!!
Welcome! Will do!
really interesting talk. In the begining you mentioned that the "wetting" of your depositions was an issue. What this addressed or solved in your studies?
I have similar interest in reducing surface tensions in solids to improve "wetting" during sintering.
Unfortunately it’s still a problem - the trick is in trying to control the defects that form when the droplets hit each other and combine
Why aren't lecture Halls build more like auditoriums instead of echo chambers? I can deal with the noice (gain set too high, or it's sitting on the A/C duct) it's the multipath frequncy smear.
kinda sad that the audio quality is so poor, should've used your lavalier mic!
Omg lead selenide that's semiconducting has....interesting applications.
I wish to be a researcher as good as you one day
Does PbSe make sense from an implementation perspective or will the potential health hazards hinder any applications?
I've always had the fantasy of using survivalist accessible methods to make a computer. One of my ideas was to make the transistors with PbS (Galena) since you could practically get that out in the wild relatively easily. other than the fact that it would be (a) easy to get, and (b) a semiconductor.... I have no idea where one would go from there. I had assumed something like the germanium "cat whisker" junctions could be formed with the right dope-ant laced wires.
Yeah, that really wouldn't work, cat whiskers make a rough diode, but you need the depletion zones to make a proper switch.
8μm? That’s thermal infrared! Sounds like that sort of tech might be replacing pyroelectric sensors in a decade or two! Though I couldn’t say whether it would be cheaper or more effective.
Sadly nah, it's not great qE in comparison to Amorphous Silicon or Vanadium Oxide, those are FAR FAR FAR FAR better and RAPIDLY dropping in price.
Very nice talk. The only thing that isn't clear to me is why you're growing PbSe on top of a III-V semiconductor - it seemed from the presentation that growing a IV-VI on a III-V is more difficult than on another IV-VI. Do we just not have means to manufacture a IV-VI substrate, so we're stuck with a III-V? Or do III-V have other nice properties that make it desirable to have a III-V below the PbSe?
Both! iii-v substrates are much cheaper, much more thermally conductive and have better mechanical strength and chemical stability than either native iv-vi substrates or the old fluorite substrates. You’re correct it WOULD be easier to do homoepi on pbse substrates but we never bothered to try because it wasn’t going to be useful.
There are also buckets and buckets of institutional knowledge surrounding iii-vs so by working with them we could get a lot more help!
Great talk, just wish the audio was a little better. Maybe you can mic yourself next time and sync it up in post?
Very interesting stuff! You mention that the effects at the interface would be more important for quantum applications than conventional semiconductor stuff. Do these rely on different properties of the materials, or are they excited differently? Or do both rely on the same property, but the quantum use case is just less fault-tolerant?
There are loads of interfacial effects in semiconductors that all rely on slightly different physics. In this case the electronic structure in one material has different symmetry than the electronic structure in the other material. Because that symmetry is sort of a fundamental property of space that’s continuously varying everywhere, that means everything has to pinch shut between the two materials in order to flip from one symmetry to the other, leading to weird things that only happen literally AT an interface and nowhere else.
The much more commonly studied “2D Electron Gas” exists at GaAs/AlGaAs interfaces and is the foundation of a lot of cool quantumy research although it’s not based on the topology/symmetry/weird stuff I was talking about here
@@AlphaPhoenixChannel Thanks! It's very interesting for me to think of the molecular-level interface and how it is created, as opposed to just assuming an instantaneous/perfect transition (to make the maths easier for field calculations etc.).
Haha yeah nothing’s as clean as the simulations and pictures xD
AH-HA!! It IS a semiconductor!! In your vid about the bean deposition I saw the sample and thought it looked like a CPU chip and left a comment rambling on about silicon semiconductors reaching their limit and then went on to photonic processors. But I was trying to figure out if you were making semiconductors and now I know you are.. neat-o! LOL :D
Is there a bandgap that corresponds to terahertz transmission?
I’m surprised that you use terms like Rocksalt and Zincblende instead of halite and sphalerite. Off putting, yet somehow also kinda charming.
Top video 👌 very insightful
This is an amazing lecture, inspiring really.
Can you do a voiceover? :D
Liked the talk even if it’s not my research field. General question : semiconductors can only be made from metalloids ?
In theory other materials can behave as semiconductors. For example, extremely tiny metal nanoparticles(
I would like to have seen the questions if that is possible
Defense video will be soon
I just loved it
I don't think the "limited by physics" is going to solve itself any time soon, its not likely that physics will change.
1:!9 like chords of elements.
You could at least filter the high pitch noise out of the video.
can all this science discussed be used to make a better microphone?!?
Lol
The corona got him.
Unfortunately the audio is very bad
Much of the same content is coming soon with better audio!
Oh noo.. I really wanted to listen to this but the sound quality is just too poor..
this is probably the worst sound quality in recorded history
You haven’t listened to nails going down a chalkboard on audio then
Pretty sure everyone in this audience had Covid after that... Also kind of interesting that apparently recording tech at all universities seems to be stuck in the 80ies.
GoPro on a chair in the front row. Very unofficial lol
Recorded on a potato
The audio is baad
Do magnetic fields affect crystal formation?