Thermodynamic Measurements via Time-Resolved Transient Conductance

Abstract

ABSTRACTRecent applications of the transient conductance technique to measurements of thermodynamic properties of Si are reviewed. The transient conductance measurements provide time-resolved data of the melt and solidification dynamics during pulsed laser irradiation. By studying these dynamics, thermodynamic properties can be measured in time and temperature regimes unaccessible by conventional techniques. Examples discussed include homogeneous nucleation, electrical properties of the supercooled liquid, and the melting temperature of amorphous Si. Homogeneous nucleation occurs at supercoolings of 500 K for quench rates near 1010 K/s, consistent with a liquid/crystal surface energy of 0.34 J/m2. Evidence of transient nucleation effects are observed at quench rates above 2 × 1010 K/s. During supercooling, the temperature dependence of the electrical conductivity of liquid Si was estimated between 1200 and 1800 K with a broad maximum observed near 1450 K. The melting temperature of amorphous Si was determined to be 220 K below the crystal melting temperature with no detectable differences between thermally unrelaxed and relaxed states.