Study of thermal and optical properties of the semiconductor CdTe by photopyroelectric spectroscopy

In this study, photopyroelectric spectroscopy (PPES) was used to obtain thermal and optical properties of CdTe thin films in the 300–1200 nm wavelength range. The samples studied were grown on glass or $BaF2$ substrates using the hot wall epitaxy technique with varying thicknesses. The normalized photopyroelectric signal intensity and its phase were independently measured as a function of wavelength $λ$ and chopping frequency $f$⁠. Equations of both the intensity and the phase of the PPES signal, taking into account the thermal and the optical characteristics of the pyroelectric detector, were used to fit the experimental results. From the fittings, we have obtained the values of thermal diffusivity coefficient $α$⁠, thermal conductivity $k$⁠, optical absorption coefficient, and the optical gap of CdTe.