Anisotropy in thermal and electronic properties of single crystal GaSe determined by the photoacoustic method

Abstract

Anisotropy in thermal and electronic properties for two directions of thermal wave propagation in the GaSe single crystal was investigated using photoacoustic (PA) frequency transmission techniques. First, the electric field of an incident polarized light beam was adjusted to be perpendicular to the c-axis (E→ ⊥c) and then parallel to it (E→ ∥ c). An obvious difference in the PA phase and amplitude spectra of the same sample for these two cases was shown. The thermal diffusivity D T obtained by the fitting procedure for these two orientations of the electric field were calculated as D T∥ =0.46×10 -5 m 2 /s and D T⊥ =0.62×10 -6 m 2 /s eg. Their ratio is about 7.4. The electronic transport parameters are also given. The carrier diffusion coefficient D∥ is 0.53×10 -3 m 2 /s and D⊥ is 0.3×10 -3 m 2 /s.