Dubyk K. Peculiarities of photoacoustic response formation in composite systems based on porous silicon matrix

The thesis is devoted to the processes of photothermal and photoacoustic transformation study in heterogeneous silicon-based structures. Here the results of mathematical simulation and experimental investigation of photoacoustic signal formation in such structures under its irradiation with square-wave and pulse laser radiation are presented. Simulation of photothermal profile formation in heterogeneous semiconductors under its irradiation with periodic modulated radiation was made. For modelled two-layered system it was shown influence of the structurally inhomogeneity on redistribution of thermal energy in investigated sample under its irradiation with square-wave modulated irradiation. Based on quasi-static approximation and rigid normal assumption, the model of photoacoustic signal formation in heterogeneous multi-layered system was proposed. It was shown that formation of the voltage signal strongly depends on a point at which thermo-elastic source is applied. The simulation of shapes of photoacoustic signal for the heterogeneous “porous silicon – bulk Si substrate” structures under its irradiation with square-wave modulated irradiation were made.