STRUCTURAL CHARACTERIZATION OF ULTRATHIN NANOCRYSTALLINE SILICON FILMS FORMED BY ANNEALING AMORPHOUS-SILICON

The fabrication and structural characteristics of ultrathin nanocrysta llization silicon films is reported. Amorphous Si layers, with nominal thicknesses in the range of 3.5-11 nm, were deposited by low-pressure chemical vapor deposition onto amorphous SiO2 and then crystallized u sing rapid thermal annealing at temperatures from 650 to 750 degrees C . High-resolution electron microscopy revealed that the resulting film s were comprised almost entirely of Si nanocrystallites with a small f raction of remaining amorphous material. The grain size in the vertica l growth direction was controlled by the thickness of the as-deposited amorphous Si film, whereas the lateral grain size was determined by a ppropriate choice of the annealing conditions. (C) 1998 American Vacuu m Society. [SO734-211X(98)01405-X].