Like a mirror in a bathroom, it is covered by water vapor when it is showered in a hot water
We applied (sputtered) a molybdenum film layer by using a magnetron sputtering process. The raw material for this vacuum coating process is a sputtering target.
In the vacuum chamber, the plasma is ignited by applying a few hundred volts of voltage and inputting argon. The plasma is made of pure argon, positively charged argon particles (argon ions) and free electrons. The electric field accelerates the positively charged argon ions toward the negatively charged cathode (target). They collide with the surface of the target and produce high kinetic energy of tens to hundreds of electron volts (eV). In some ways, the whole process is similar to a billiard game in that argon particles continuously expel atoms from the surface of the sputtering target. In this way, the coating material is slowly eroded. The atoms that are off the sputtering target will be directed through the vacuum chamber onto the opposite substrate where they are deposited as a thin layer. (Like a mirror in a bathroom, it is covered by water vapor when it is showered in a hot water).