  The photoacoustic method with piezoelectric detection for the simultaneous
evaluation of the thermophysical properties is proposed. The approach is based
on the settling of an additional heat sink for redistribution of heat fluxes
deposited on the sample surface. Firstly, the approach was tested on the porous
silicon with well-defined morphology and well-studied properties. Then, heat
capacity and thermal conductivity of silicon nanowires arrays have been
investigated by recovering the experimental data through numerical simulations.
The decrease of heat capacity and effective thermal conductivity of the samples
upon increasing thickness and porosity of the sample is observed. Such behavior
could be caused by the increase of the structure heterogeneity. In particular,
this can be related to larger disorder (increased density of broken nanowires
and larger porosity) that appears during the etching process of the thick
layers.
