Fabrication of Nanocrystalline Silicon with Small Spread of Particle Size by Pulsed Gas Plasma

Abstract

We have investigated the formation of nanocrystalline Si (nc-Si) in SiH₄ plasma using a pulsed-H₂ gas supply by very-high-frequency (VHF; 144 MHz) excitation. Nanocrystalline Si is formed in the gas phase of a SiH₄ plasma cell by the coalescence of radicals. The particle size of nc-Si is determined by the growth time of nc-Si in the plasma cell. Supplying H₂ into SiH₄ plasma enhances nucleation of nc-Si. When the H₂ gas supply is turned off, nucleated nc-Si particles grow larger in SiH₄ plasma. In the next cycle of H₂ gas supply, nc-Si particles grown in the previous cycle are pushed out of the cell into the deposition chamber. Using this method, fabrication of nc-Si with a diameter around 8 nm and a narrow spread (±1 nm) of particle size was realized.