The effect of metal cluster formation on THz range spectroscopy

The present paper discusses terahertz (THz) spectroscopy of ion-implanted layer embedded metal particles. MgO (001) single crystals were implanted with − 75 KeV Au ions at an ion dose of 1 × 1018 cm− 2, later annealed in air at 1100 K for 1 h. After the each process, the transmittance T spectrum ranging from 250 to 2000 nm, and the reflectance R spectrum ranging from 1.2 to 21 THz were measured. The T spectra show the embedded Au particles were formed in the implanted layer. The notion of an effective dielectric function was brought to evaluate the two-phase (Au–MgO) composite material. Consequently, the R THz spectrum analysis showed the dielectric function of the implanted MgO. This dielectric function reveals that dispersion by the optical phonons. The formation of embedded Au clusters in MgO shifted the resonance frequency of the optical phonon, and increased the damping constant. Results show that the THz spectrum reflects the introduced defects and the lattice deformation caused by the ion implantation and Au cluster formation.