Crystalline silicon on insulators by graphoepitaxy

Graphoepitaxy is a new technique that uses artificial surface relief structures to induce crystallographic orientation in thin films. A simple model for graphoepitaxy is presented which predicts that materials that can be deposited on smooth amorphous substrates to produce a crystalline texture can be uniformly oriented by appropriate surface relief structures. Recently, graphoepitaxy has been used to achieve uniformly oriented silicon films 0.5 µm thick over surface relief gratings etched into amorphous fused silica substrates. The silicon was first deposited as an amorphous film and then crystallized using a scanned Ar laser beam. The mean [100] directions in the silicon were parallel to the grating and perpendicular to the substrate plane. Films uniformly doped with phosphorous (2.4 × 10¹⁷atoms/cm³) had an electron mobility at least 40% of the bulk value.