A single-crystal silicon layer is formed by graphoepitaxy from a low-melting-point metal layer which contains dissolved polycrystalline or amorphous silicon, or from a melt of a silicon-containing low-melting-point metal, using step differences formed on a substrate as a seed for the epitaxial growth. This single-crystal silicon layer is used as dual-gate MOSTFTS, or bottom-gate MOSTFTS, of an electrooptical device such as an LCD integrating a display section and a peripheral-driving-circuit section. This process enables production of a uniform single-crystal silicon thin-film having high electron/hole mobility at a relatively low temperature. The display section includes LDD-nMOSTFTs or pMOSTFTs having high switching characteristics and a low leakage current. The peripheral-driving-circuit section includes cMOSTFTs, nMOSTFTs, pMOSTFTs, or a combination thereof, having high driving ability.