Semiconducting silicide photonic devices

Abstract

Si/β-FeSi 2 /Si (SFS) structures with β-FeSi 2 particles on Si(001), and SFS structures with β-FeSi 2 continuous films were epitaxially grown on both Si(001) and Si(lll) substrates by molecular-beam epitaxy (MBE). All the samples exhibited the same photoluminescence (PL) peak wavelength of approximately 1.54 μm at low temperatures. However, the PL decay times for the 1.54 μm emission were different, showing that the luminescence originated from different sources. The decay curves of the SFS structures with β-FeSi 2 continuous films were fitted assuming a two-component model, with a short decay time (τ∼10 ns) and a long decay time (τ∼100 ns), regardless of substrate surface orientation. The short decay time was comparable to that obtained in the SFS structure with β-FeSi 2 particles. The short decay time was due to carrier recombination in β-FeSi 2 , whereas the long decay time was probably due to a defect-related D1 line in Si. We obtained 1.6 μm electroluminescence (EL) at a low current density of 2 A/cm 2 up to around room temperature. The temperature dependence of the EL peak energy of the SFS diodes with β-FeSi 2 particles can be fitted well by the semi-empirical Varshni's law. However, EL peak positions of the SFS diodes with the β-FeSi 2 films showed anomalous temperature dependence; they shifted to a higher energy with increasing temperature, and then decreased. These results indicate that the EL emission originated from several transitions.