Spectroscopic Properties of Semiconductor Nanoparticles near the Solid-to-Liquid Phase Transition

Abstract

Gas-phase synthesis of semiconductor nanoparticles is often supported by optical in situ measurements to determine the particle size, phase, and volume fraction. These attributes are connected to the optical properties of these particles, which depend strongly on the temperature and particle size as well as the phase transition near the melting point. To support such measurements, we derive a Lorentz-oscillator model for solid silicon and germanium with temperature- and particle-size-dependent transition energies, line widths, and oscillator strengths. The model yields the complex dielectric function that is then processed using Mie theory to calculate size-dependent absorption and scattering cross-sections for nanoparticles as well as nanoparticle aerosols.