Electron-beam evaporation is a physical vapour deposition method for depositing thin films of metals, oxides and semiconductors in a high vacuum environment. Ultra high purity coating material is placed inside a vacuum chamber, typically as pellets in a crucible. Electron energy is used to heat these pellets, causing the coating material to enter the gas phase. Due to the vacuum environment, the evaporated particles can travel to the substrate without colliding with foreign particles, where they then condense on the substrate surface in a thin film. Electron beam evaporation is used to deposit electronic and optical films for the semiconductor industry and has applications in displays and photovoltaics. High melting point materials can be deposited at high deposition rates, making this a preferred process for refractory metal and ceramic films.