What is Deposition? (Definition and Examples)

Deposition (also called Desublimation) is the thermodynamic phase change where a Gas turns directly into a Solid, completely bypassing the liquid phase.

• This happens when the temperature drops extremely rapidly.
• It is the exact opposite of Sublimation (where a solid turns directly into a gas, like Dry Ice).

• Frost on Windows: On a freezing winter morning, you often see solid ice crystals (frost) forming directly on your car's windshield. The invisible water vapor (gas) in the air hits the freezing cold glass and instantly turns into solid ice without ever becoming water drops.
• Formation of Snow: High up in the freezing clouds, water vapor turns directly into solid snowflakes. If it turned into liquid water first, it would fall as rain or sleet, not soft snow.
• Soot in Chimneys: When wood burns, it releases hot carbon gases. As these gases travel up a cold brick chimney, they instantly deposit onto the walls as solid black soot.

In manufacturing, engineers use a process called Chemical Vapor Deposition (CVD). They take a metallic gas and cool it rapidly onto a silicon surface to create an incredibly thin, perfect layer of solid metal. This exact process is used to manufacture the microchips inside your smartphone and computer.