The structure and optical properties of silicon ultrafine particles deposited by the gas-evaporation technique with a supersonic jet nozzle

Abstract

The structure and properties of silicon (Si) ultrafine particles deposited on Si or SiO 2 substrates at 300 K by the gas-evaporation technique 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 deposition 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 structure of Si ultrafine particles deposited by this technique were studied by the transmission electron microscopy (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 evaporation chamber is increased from 1 to 5 torr. It is found that this technique can fabricate Si ultrafine particles with better uniformity in the size and better crystallinity than the conventional gas-evaporation technique.