Dielectric relaxation and transport in porous silicon

摘要: Results of dielectric spectroscopy study porous silicon samples in the frequency range 20 Hz-1 MHz and temperature 173-493 K. are presented. We found three relaxation processes that dominate at low, moderate high temperatures, respectively. At low temperatures dispersion is composed two Cole-Cole with activation energies 0.2 0.3 eV, complex function exhibits frequency-dependent power laws well described by Jonscher empirical terms. above 400 K we a large dc conductivity, energy 0.46 an additional Havriliak-Negami process typical times order 10 - 3 sec. Following our findings, propose comprehensive model, which assigns these to fractal geometry thermally activated from localized delocalized electronic states nanocrystallites. In addition, argue high-temperature cannot be explained on basis response mode cooperative appears temperatures.