I want to show off a little. Well, I want to both show off some of my own work and be amazed by it. I work with superlattices, which means that I layer alternating materials (like stacking Legos of two different colors). We measure the layer thicknesses in “unit cells”, with one unit cell being one complete layer of the crystal structure and about 0.4 nm thick. That’s super, super thin. It can be hard to make a superlattice where one of the materials is a single unit cell thick. But for my most recent experiments, I’ve been trying.
I recently got an image back from a collaborator who does transmittion electron microscopy (TEM). With TEM, you take a cross-section image of the sample and can image individual atoms. In a good superlattice, the atoms should be stacked in an orderly fashion and you should see alternating layers of the two different materials. If I’ve made a good quality superlattice, there should be a clear boundary between the two materials. This can be hard to achieve when you aim to make one of the materials only 1 unit cell thick. But look what I did!
I’m ultra proud of this image. First, all the atoms stack nicely, which tells me I wasn’t wasting my time making disordered superlattices (hooray!). And secondly, look how thin the darker lines are. That’s a single unit cell! And just how cool is it that we can see individual atoms? It’s images like this that constantly makes me step back and realize how amazing science can be.