Photoacoustic characterization of semiconductors: Transport properties and thermal diffusivity in GaAs and Si

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.