• Vanhellemont, Jan
• Biest, Omer Van Der
• Swarnakar, Akhilesh Kumar

Abstract

<jats:p>The vibrational properties of single crystal Si and Ge are studied between room and melting temperature <jats:italic>T</jats:italic><jats:sub><jats:italic>m</jats:italic></jats:sub> using the impulse excitation technique. From the measurements, the temperature dependent Young’s moduli <jats:italic>E</jats:italic><jats:sub><jats:italic>&lt;ijk&gt;</jats:italic></jats:sub> are extracted in the &lt;100&gt;-, &lt;110&gt;- and &lt;111&gt;- directions. For both semiconductors, the Young’s moduli decrease smoothly with increasing temperature and retain high values up to <jats:italic>T</jats:italic><jats:sub><jats:italic>m</jats:italic></jats:sub>. Using the semi-empiric Wachtman's equation allows an excellent fit to the experimental data for the temperature dependence of <jats:italic>E</jats:italic><jats:sub><jats:italic>&lt;100&gt;</jats:italic></jats:sub>, <jats:italic>E</jats:italic><jats:sub><jats:italic>&lt;110&gt;</jats:italic></jats:sub> and <jats:italic>E</jats:italic><jats:sub><jats:italic>&lt;111&gt;</jats:italic></jats:sub> between room temperature and 0.6<jats:italic>T</jats:italic><jats:sub><jats:italic>m</jats:italic></jats:sub>,. For higher temperatures, the Young's moduli decrease faster than predicted by Wachtman's equation. In the case of Ge, an apparent enhanced softening is observed starting from about 850 ºC which is due to a loss of Ge material, leading to a decrease of sample dimensions and weight.</jats:p>

Topics

• impedance spectroscopy
• single crystal
• semiconductor
• melting temperature