THERMAL DIFFUSIVITY OF Si (100) AND GaSb SINGLE CRYSTALS

In this work, we report the characterization of Si (100) and GaSb (111) single crystals by using Raman spectroscopy and a photoacoustic cell in open and closed configuration. For III-V compound semiconductors of the zinc-blende crystal structure, Raman spectra generally show two peaks. The lower-frequency peak corresponds to TO phonons, and the higher frequency peak corresponds to LO phonons. A strong peak was found at 226 cm(-1) and a weak peak at 237 cm(-1), which are the TO and LO modes, respectively. Raman spectrum of GaSb (111) show that the integrate intensity of TO mode is greater than LO mode due to disoriented of the single crystal. In order to obtain the thermal diffuivity, the crystals were exciting by means of solid-state lasers of wavelengths of 650 nm and 535 nm, respectively. The results of the thermal diffusivity of single crystals, obtained from the Rosencwaig and Gersho (RG) model were analyzed according to the crystallographic orientation. We have also discussed the contribution of the non-radiative recombination to the photoacustic signal from surface and bulk depending on the type of cell and excitation of the laser line.