An amorphous semiconductor, also called thin film, is a non-crystalline semiconductor material that has no long-range order. Although easier and cheaper to make than a crystalline semiconductor, it is less efficient and slowly degrades over time. A layer of amorphous semiconductor, such as copper indium diselenide, cadmium telluride, gallium arsenide, or amorphous silicon, a few microns or less in thickness, is used to make solar cells.