Open Access Nano Express

Opto-structural studies of well-dispersed silicon nano-crystals grown by atom beam sputtering

Nupur Saxena1*, Pragati Kumar2, Debulal Kabiraj1 and Dinakar Kanjilal1

Author Affiliations

1 Inter University Accelerator Centre, P.O. Box 10502, Aruna Asaf Ali Marg, New Delhi, 110 067, India

2 Department of Physics, Bareilly College, Bareilly, Uttar Pradesh, 243005, India

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Nanoscale Research Letters 2012, 7:547  doi:10.1186/1556-276X-7-547

Published: 3 October 2012

Abstract

Synthesis and characterization of nano-crystalline silicon grown by atom beam sputtering technique are reported. Rapid thermal annealing of the deposited films is carried out in Ar + 5% H2 atmosphere for 5 min at different temperatures for precipitation of silicon nano-crystals. The samples are characterized for their optical and structural properties using various techniques. Structural studies are carried out by micro-Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy, and selected area electron diffraction. The optical properties are studied by photoluminescence and UV-vis absorption spectroscopy, and bandgaps are evaluated. The bandgaps are found to decrease after rapid thermal treatment. The micro-Raman studies show the formation of nano-crystalline silicon in as-deposited as well as annealed films. The shifting and broadening in Raman peak suggest formation of nano-phase in the samples. Results of micro-Raman, photoluminescence, and TEM studies suggest the presence of a bimodal crystallite size distribution for the films annealed at higher temperatures. The results show that atom beam sputtering is a suitable technique to synthesize nearly mono-dispersed silicon nano-crystals. The size of the nano-crystals may be controlled by varying annealing parameters.

Keywords:
Silicon nano-crystals; Atom beam sputtering; Rapid thermal annealing; TEM; Raman; Photoluminescence; 81.07; Bc68.37; Lp78.67; Bf