If you read the scientific literature, you see the familiar subatomic particles you learned about in school: protons, neutrons, and electrons. If you are young enough, you see others you probably heard about, too, like quarks and gluons. But recently there has been a lot of buzz about excitons and even some transistor circuits demonstrated that use them. But what is an exciton?

It actually sounds like a subatomic particle, but it is a little more complicated than that. An exciton is a bound state of an electron and an electron hole and is technically a boson. You are probably familiar with the idea of an electron hole from semiconductor physics. Technically, it is a quasiparticle. The reason scientists are interested in the beast is that it can transport energy without transporting net electric charge. That is, the state itself is neutral, but also contains energy. Continue reading “What’s An Exciton?” →