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)
DOI
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) .
Annotation
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.

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