Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD

• Main Authors: Muller TFG, Knoesen D, Halindintwali S, Arendse CJ, Malgas GF, Oliphant CJ, Motaung DE, Mwakikunga BW
• Format: Article
• Language: English
• Published: SpringerOpen 2009-01-01
• Series: Nanoscale Research Letters
• Subjects: Hot-wire CVD; Quantum size effects; Nano-crystallite; Optical band gap
• Online Access: http://dx.doi.org/10.1007/s11671-008-9243-0
• ISSN: 1931-7573; 1556-276X

<p>Abstract</p> <p>We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200&#8211;700 &#176;C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as &#8801;Si&#8211;H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures &#8805;400 &#176;C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.</p>