THE STRUCTURE AND OPTICAL-PROPERTIES OF SILICON ULTRAFINE PARTICLES DEPOSITED BY THE GAS-EVAPORATION TECHNIQUE WITH A SUPERSONIC JET NOZZLE

The structure and properties of silicon (Si) ultrafine particles depos ited on Si or SiO2 substrates at 300 K by the gas-evaporation techniqu e with a supersonic jet nozzle were studied. The technique is designed to deposit Si ultrafine particles at the supersonic speed, resulting from the differential pressure between the Si evaporation and the Si d eposition chamber The size of Si ultrafine particles can be controlled with the gas pressure in the evaporation chamber and the distance of the jet nozzle from the Si evaporation boat. The crystallinity and str ucture of Si ultrafine particles deposited by this technique were stud ied by the transmission electronmicroscopy (TEM) and the transmission electron diffraction (TED). With the fixed distance of 5 cm, the size increases from 7 to 10 nm when the pressure of argon gas in the evapor ation chamber is increased from 1 to 5 torr. It is found that this tec hnique can fabricate Si ultrafine particles with better uniformity in the size and better crystallinity than the conventional gas-evaporatio n technique. (C) 1997 Acta Metallurgica Inc.