J. Phys. IV France
Volume 125, June 2005
Page(s) 169 - 171

J. Phys. IV France 125 (2005) 169-171

DOI: 10.1051/jp4:2005125039

Determination of thermal and optical parameters of the semiconductor CdTe by photopyroelectric spectroscopy

J.E. de Albuquerque, P.M.S. de Oliveira and S.O. Ferreira

Departamento de Física, Universidade Federal de Vicosa, 36571-000 Vicosa/MG, Brazil

In this study, photopyroelectric spectroscopy was used to obtain thermal and optical properties of CdTe in the $300<\lambda<1200$ nm wavelength range, where $\lambda$ is the wavelength. The normalized photopyroelectric intensity signal $V_n(\lambda)$ and its phase $f_n(\lambda)$ were independently measured, as well as the intensity Vn(f) and the phase Fn(f) (f being the chopping frequency) for a given $\lambda$ of the saturation part of the PPES spectrum. Equations of both the intensity and the phase of the PPES signal, taking into account the thermal and the optical characteristics of the pyroelectric (PVDF) detector, were used to fit the experimental results. From the fitting in the graph Fn(f) versus f1/2, we obtained, with great accuracy, the value of thermal diffusivity coefficient $\alpha$. From the fitting in the graph Vn(f) versus f, we obtained the thermal conductivity k. The specific heat c of the sample is then directly derived from the relation $k=\rho c\alpha$, where $\rho$ is the mass density, valid for a stationary state. From the fittings in the graphs $V_n(\lambda)$ versus $\lambda$ and $f_n(\lambda)$ versus $\lambda$, we obtained the optical absorption coefficient and the optical gap of the CdTe.

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