Photopyroelectric back detection configuration for thermal diffusivity measurement of undoped and doped GaSb semiconductors

Photopyroelectric technique in back detection configuration (BPPE) was used to investigate thermal diffusivity measurement of undoped and doped GaSb bulk samples. A theoretical model was developed and specific design of pyroelectric sensor based on PVDF film of 25 mu m thickness was constructed. The methodology is based on a designed back photopyroelectric detection cell and thermal diffusivity value is obtained directly as a result of a scan of the BPPE phase and amplitude signal as a function of square root modulation frequency. This method involves the thermally thick limit of the pyroelectric signal in the standard BPPE. To avoid the conventional requirement for set-up transfer function a signal normalization procedure is implemented. Obtained thermal diffusivity coefficients by means of this technique are 16.7 +/- 0.5* 10(-6) m(2)s(-1), 6.3 +/- 0.3 * 10(-6) m(2)s(-1), and 7.3 +/- 0.2 * 10(-6) m(2)s(-1) respectively for undoped GaSb, Te-doped GaSb and Zn-doped GaSb semiconductors. By studying samples of GaSb with different types of doping (doping with Te and with Zn) we notice a change in the thermal diffusivity function of doping.