Hi guys in the last video we talked about nano switches in this video We will take a look at nano circuit boards and for that Frank took us to his working space Tell us more about that Frank. Where are we now? We are here at the Institute for material science more precisely that we are at the chair of material science and non technology of

Professor Connie Berti, I'm working with the scanning tunneling microscope in the subgroup with Francesca moresco Okay, and can you show me how this nano circuit board works? Yeah, maybe therefore we can go into the lab. Yeah, sure. Okay, let's go

So here we are now in our lab. You might know this from Basel this machine. Yeah, that's an STM right exactly This is scanning tunneling microscope. And here we do all our experiments on the different surfaces Well, I've brought this very old circuit board with me and you can actually still see these small traces on here Does it look like that in the nano scale as well? What we have is

Silicon a planar silicon surface crystal planar means entirely flat exactly. This is entirely flat which we can Heat and then cool slowly down and then we get this time arrows rows of two

silicones displayed by the red brackets Silicon itself is highly reactive so There's three bonds and we are using the hydrogen to Make it not as reactive. Okay, so the hydrogen is the white stuff on top there exactly The white brackets are the hydrogen atoms and hydrogen means H2, right?

Exactly hydrogen means H2, but in this case we need atomic hydrogen so just H The point is that here we need exactly one hydrogen for one silicon atom So therefore we need to crack the hydrogen. Okay, how do you do that?

And cracking means we insert into our vacuum chamber molecular hydrogen and have their tungsten wire which we heat up to 2,000 degrees and by heating the filament we can crack the hydrogen into two parts and this binds then to the silicon Surface atoms so then you got an isolating layer on top, but that's not a circuit board yet, right?

Exactly, but what we can do we can use our STM tip and extract hydrogens from the surface we go with our tip over one special hydrogen atom Make a voltage pulse and kick off one hydrogen. Therefore we get then this kind of wires

So you have a wire there, right? Could you theoretically send an electric pulse through there exactly in theory we could of course Send an electric pulse there But with our STM machine it is not possible Are there any other ways to build such a small wire? We have the possibility of course to build a molecular wire

Okay, could you show me that as well? Yeah, we can have a look on that too Cool, and we'll take that for our next video, which you will as always find linked below I'll see you there and have a good time. Bye. Bye