Observation of Fano resonance in heavily doped<i>p</i>-type silicon at room temperature

Abstract

We report the observation of a resonance in the infrared-absorption spectrum of heavily boron-, aluminium-, and gallium-doped silicon at room temperature. This resonance occurs near the frequency of the zone-center optical phonon (517 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) and is attributed to a discrete-continuum Fano-type resonant interaction between the optical phonon and direct inter-valence-band transitions of holes. The optical-phonon transitions are allowed due to the disruption of symmetry of the crystal lattice by acceptor atoms. The dependence of the resonance on doping level is investigated.