Epitaxial explosive crystallization of amorphous silicon

It is shown that amorphous silicon can be transformed to monocrystalline silicon via an explosive epitaxial crystallization process induced by pulsed laser irradiation. 370-nm-thick amorphous Si layers, buried beneath a 130-nm-thick crystalline surface layer, were irradiated with a 32 ns ruby laser pulse. Real-time reflectivity measurements indicate that internal melting can be initiated at the amorphous-crystalline interface, immediately followed by explosive crystallization of the buried amorphous Si layer. Channeling and cross-sectional transmission electron microscopy reveal that explosive crystallization proceeds epitaxially with formation of twins extending into the sample. The crystal growth velocity is determined to be 16.2±1.2 m/s, close to the fundamental limit for crystalline ordering at a liquid Si/Si(100) interface.