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Using two different photoacoustic techniques for a two-layer system of variable thickness, we show that the thermal diffusivity and the thermal conductivity are completely determined, based upon the effective-sample model widely used in heat-transfer problems. A procedure to establish a standard photothermal technique for measuring both the thermal diffusivity and the thermal conductivity is also discussed.

The photoacoustic signal of two semiconductor samples is investigated as a function of the modulation frequency in a heat-transmission configuration. It is shown that, in the frequency range where the sample is thermally thick, the signal amplitude and phase can single out the different fast and slow nonradiative recombination heat sources responsible for the photoacoustic signal. The characterization of the thermal and the carrier transport properties is discussed and some practical procedures for this purpose are also outlined.