Indirect Optical Absorption of Single Crystalline beta-FeSi2

TL;DR

This study examines the optical absorption properties of beta-FeSi2 single crystals, revealing phonon structures and exciton transition energies near the fundamental absorption edge through transmission measurements.

Contribution

It provides detailed measurements of phonon energies and exciton transition energies in beta-FeSi2, enhancing understanding of its optical properties at low temperatures.

Findings

Phonon energy of 0.031 eV identified.

Exciton transition energy of 0.814 eV at 4K determined.

Clear phonon structure observed in low-temperature spectra.

Abstract

We investigated optical absorption spectra near the fundamental absorption edge of beta-FeSi2 single crystals by transmission measurements. The phonon structure corresponding to the emission and absorption component was clearly observed in the low-temperature absorption spectra. Assuming exciton state in the indirect allowed transition, we determined a phonon energy of 0.031 +- 0.004 eV. A value of 0.814 eV was obtained for the exciton transition energy at 4K.