Dielectric and ac conductivity studies in as-grown Ga2Te3crystals with the defect zinc-blende structure (original) (raw)

Ga 2 Te 3 crystallizes in the zinc-blende structure where one-third of the cation sites are vacant. The dielectric properties of asgrown Ga 2 Te 3 crystals have been studied in the frequency range from 10 2 to 10 9 Hz. Below room temperature, the dielectric constant is around 20 and almost independent of temperature. The ac conductivity is found to obey a power law s ac $ v s , with s $ 1 indicating that the conduction is due to hopping of localized charge carriers. Above room temperature the dielectric constant shows an S-shaped step-like increase up to a very large value around 10 4. The relaxation is found to be of thermal activated Debye type, the relaxation time changes as t ¼ t 0 expðE t =kTÞ (E t % 0:27 eV). The activation energy of the relaxation nearly coincides with that deduced from conductivity. These results are analyzed using the Maxwell Wagner model and the space charge model.