A Study of the Evolution of the Silicon Nanocrystallites in the Amorphous Silicon Carbide Under Argon Dilution of the Source Gases

Author(s) A. Kole , P. Chaudhuri
Affiliations Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata – 700032
Е-mail erak@iacs.res.in
Issue Volume 3, Year 2011, Number 1, Part 1
Dates Received 04 February 2011, published online 23 March 2011
Citation A. Kole, P. Chaudhuri, J. Nano- Electron. Phys. 3 No1, 155 (2011)
PACS Number(s) 61.46.Bc, 68.37.Og, 78.30.Ly 78.67.Hc, 81.07.Bc
Key words Silicon carbide (9) , RF-PECVD, AR dilution, Optical band gap (7) , Si quantum dots, Quantum confinement (5) .
Structural evolution of the hydrogenated amorphous silicon carbide (a-SiC:H) films deposited by rf-PECVD from a mixture of SiH4 and CH4 diluted in Ar shows that a smooth transition from amorphous to nanocrystalline phase occurs in the material by increasing the Ar dilution. The optical band gap (Eg) decreases from 1.99 eV to 1.91 eV and the H-content (CH) decreases from 14.32 at% to 5.29 at% by increasing the dilution from 94 % to 98 %. at 98 % Ar dilution, the material contains irregular shape Si nanocrystallites with sizes over 10 nm. Increasing the Ar dilution further to 98.4 % leads to a reduction of the size of the Si nanocrystals to regular shape Si quantum dots of size about 5 nm. The quantum confinement effect is apparent from the increase in the Eg value to 2.6 eV at 98.4 % Ar dilution. Formation of Si quantum dots may be explained by the etching of the nanocrystallites of Si by the energetic ion bombardment from the plasma.