This is a common experiment to demonstrate how to grow a crystal. Crystals are very interesting materials and many crystals are useful for making electronic devices and furthering new technological advances. On some days I get to stand next to the shiny vacuum chamber used to grow crystals. It fills the experimental station almost completely with stainless steel pipes, wires, hoses, and buzzing vacuum pumps. Inside the ultra-clean vacuum chamber, a small, flat, silicon substrate shines like a mirror.
Reactive gases fill the chamber and rain down onto the shiny substrate.
As the atoms stick to the surface, a crystal grows one layer at a time. While this is going on, x-rays hit the film and exit the chamber through special windows. By analyzing the scattered x-rays, scientists can learn about how the atoms stick and move around on the substrate before they settle to grow a new crystalline material. Material designers are trying to create a source of blue light. Blue light has a shorter wavelength than red light, which has a number of technological advantages.