GEOG 777

[MUSIC PLAYING] ROMAN ENGEL-HERBERT: Hello, and welcome everybody to this online course, MATSE 413, solid state materials. My name is Dr. Engel-Herbert, and I'm the instructor of this course. And you see me here in my lab. This is the molecular beam epitaxy lab at Penn State University. And what we are doing here is we are putting the things that we're learning in this course to practice. Not necessarily me, but in fact, this is what the students do. They put this to practice and I'm excited to bring this content of solid state materials to you.

So what do we do in this lab? You can see here a very large shiny system. This system is what we call a molecular beam epitaxy system. And what we're doing here is we are building materials, solid state materials, from the ground up.

So we are evaporating elements, and we are building and arranging them with atomic scale precision. And the reason why we do this is we want to understand much better from the ground up how solid state materials work and how do we engineer the desired properties into these material systems?

And part of what you're going to be learning in this course is what the underlying fundamentals are -- what's the physics, what's the chemistry, and what's the mechanics and what holds it all together. And it actually turns out that what holds it together is the fundamentals of solid state materials. And this is very exciting for me, and I hope you're going to enjoy this as well.

I love research. But I even more love teaching, Teaching students like you. And teaching, in fact, has a long-standing tradition in my family. My dad is a teacher, my mom is a teacher, and I saw how rewarding it was for them to teach people and to spread the excitement about certain topics. In the beginning, you are not quite sure why you need this. But then as you have somebody helping you delve more and more into it and see the fascination, it's very rewarding. And then see that students like you appreciating and are fascinated by it as well, is something that is very fulfilling.

Why do I like material science? Well, I am a physicist by training. I did my PhD back in Germany at the Institute of Solid State Electronics. So you can see already in the title, I was always drawn to solid state physics, and with that, solid state materials. Because one of the things that I learned when I was working in the lab as a graduate student is that on top of the food chain is actually not the physicist, it's the material scientist. Because the material scientist creates materials, and you can only make discoveries in new or improved materials. And in fact, those discoveries, then going to have implications into today's life. And so I decided to move away from physics and do a little bit more of the material science to be part of those exciting discoveries. And it turns out that the fundamentals of solid state materials are actually at the heart and at the core of these kinds of discoveries.

Why are we interested in solid state materials? That's a good question. You probably want to Google it. But before you Google it, realize what you're doing with your phone and what you're holding in your hand. You hold a lot of solid state materials in your hand.

Think about how you're interacting with information and with content. You're typing it on your transparent screen. The transparent screen has a backlit display. There's a light-emitting diode in it. There's a processor that has to work with your information, with your input. And then this information needs to be sent off to the cloud, which are also processes and memories that make sense of your request to then retrieve the information and bring it back to you on the screen. So there's a whole lot of solid state materials we actually have to go through to get an answer of the question, what are solid state materials? And it gives you an idea of how much our daily life is influenced by solid state materials.

ROMAN ENGEL-HERBERT: Let me tell you a little bit about the content of this online course. And so the way it's been structured is that we're going to first ask ourselves, what does it mean? What is our study object? What are solid-state materials?

I want you to go with me a little bit back in time and characterize what kind of different states of mater we have and why the condensed phase of matter is so interesting to us.

And what we're going to do then is we're going to start taking them apart bit by bit; we're going to look at what are the building blocks of matter? Why do they even arrange in the way they arrange?

There's a periodic arrangement we call crystals, and we want to understand the driving forces behind this. And as soon as we understand why do they form, we're going to try to be a little bit more quantitative. We're going to try to understand what are the orders of magnitude of forces interacting between these particles finally forming the crystal.

And from there on we're going to start understanding what happens if we put them into different environments, like temperature and pressure, just to see how these things react. What are the inner works of these building blocks of matter? And then very soon after, we're going to start looking at electrons. How do electrons behave in solid-state materials? It turns out they behave much different. They not only behave like particles, they actually also behave like waves.

So we're going to start understanding the fundamentals of quantum mechanics, which is behind the properties of electrons in solid-state materials. And this is going to give you a good outlook on many, many applications that we see in today's life, such as a light-emitting diode. This is what makes this lab have some light inside. Of lasers, something that I'm using a lot in the lectures. Not so much in this online course.

But there's a lot of excitement and exciting applications of solid-state materials, and we are all going to touch upon them in the later part of the course. So what I would suggest is let's get out of the lab. Let's take off the safety glasses and get going.