LEDs - The Basic Phenomenon

In other states of matter, in other materials, you can have quasi particles with all kinds of behaviors. Holes are... It's very, very important to have positively charged particles that you can manipulate much more freely and that are cheaper to make than protons. So holes are not just fun, not just interesting, but they're extremely useful. They're absolutely essential in the design of light emitting diodes, of transistors, of all aspects of microelectronics that dominate our world today.