Elastic Properties of Crystalline鈥揂morphous Core鈥揝hell Silicon Nanowires

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• 作者：Sevak Khachadorian ; Konstantinos Papagelis ; Ken Ogata ; Stephan Hofmann ; Matthew R. Phillips ; Christian Thomsen
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 28, 2013
• 年：2013
• 卷：117
• 期：8
• 页码：4219-4226
• 全文大小：473K
• 年卷期：v.117,no.8(February 28, 2013)
• ISSN：1932-7455

文摘

The pressure behavior of Raman frequencies and line widths of crystalline core-amorphous shell silicon nanowires (SiNWs) with two different core-to-shell ratio thicknesses was studied at pressures up to 8 GPa. The obtained isothermal compressibility (bulk modulus) of SiNWs with a core-to-shell ratio of about 1.8 is 20% higher (lower) than reported values for bulk Si. For SiNWs with smaller core-to-shell ratios, a plastic deformation of the shell was observed together with a strain relaxation. A significant increase in the full width at half-maximum of the Raman LTO-peak due to phonon decay was used to determine the critical pressure at which LTO-phonons decay into LO + TA phonons. Our results reveal that this critical pressure in strained core鈥搒hell SiNWs (4 GPa) is different from the reported value for bulk Si (7 GPa), whereas no change is observed for relaxed core鈥搒hell SiNWs.