Indirect optical absorption of single crystalline β-FeSi2

Abstract

We investigated optical absorption spectra near the fundamental absorption edge of β-FeSi 2 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. * Electronic address: udono@ee.ibaraki.ac.jp 1

Growth of β-FeSi2 particles on silicon by reactive deposition epitaxy

“…According to a recent report on the optical absorption properties of singlecrystalline ␤-FeSi 2 [5], an indirect energy gap was observed in the low temperature spectra, clarifying thus the band gap nature. The successful fabrication of ␤-FeSi 2 light-emitting diode operating at the wavelength of about 1.5 m demonstrated the potential capability of ␤-FeSi 2 as a light-emitting material [6].…”

Indirect optical absorption and origin of the emission from β-FeSi2 nanoparticles: Bound exciton (0.809 eV) and band to acceptor impurity (0.795 eV) transitions

“…24 The spectrum on the low energy side suggests a step behavior ͑with phonons͒, characteristic of an indirect fundamental gap material. 25 In this figure, the points corresponding to E ph a ͑absorption, 0.7802 eV͒ and E ph e ͑emission, 0.8418 eV͒ refer to the thresholds of the step of phononassisted indirect transition. Their energy difference, 61.6 meV represents exactly two phonons replicas with energies equal to 0.0308 eV, which has also been identified as active by micro-Raman experiments ͑the highest-intensity peak, see Fig.…”

“…26 A theoretical calculated value for this energy was estimated to be 35 meV. 27 We have adjusted theoretical curves to the experimental data ͑in a process similar to the one used by Udono͒ 25 through the following approximate expression for optical absorption, assuming indirect allowed optical transition:…”

Structural and transport properties of β-FeSi2 [100] oriented thin film on Si(001) substrate

“…b-FeSi 2 shows semiconducting properties having energy band gap (E g ) of 0.85 eV. In recent years, semiconducting silicide has attracted considerable interest because it is expected to exhibit new possibilities for the integration of electronic and optoelectronic applications with the currently existing Si technologies [2,3].…”