A method of growing an epitaxial layer on a substrate from a molten material. The substrate crystal is placed in a slider and the material to be deposited is contained in molten form in a ‘boat’. The melt is supercooled to just below the solidification temperature. As the slider containing the substrate material is moved slowly across the surface of the melt, atoms solidify onto the crystal substrate. This method of epitaxy is most useful for III–V or II–VI compound semiconductors, particularly gallium arsenide substrates. It has limitations and is losing popularity, but is inexpensive and capable of growing many material compositions; it is therefore still used for some applications, such as light-emitting diodes, that do not require such thin uniform high-quality layers as are required for microwave devices.