Low-Frequency Dielectric Relaxation in Structures Based on Macroporous Silicon with Meso-Macroporous Skin-Layer

The spectra of dielectric relaxation of macroporous silicon with a mesoporous skin layer in the frequency range 1-10(6) Hz during cooling (up to 293-173 K) and heating (293-333 K) are presented. Macroporous silicon (pore diameter approximate to 2.2-2.7 mu m) with a meso-macroporous skin layer was obtained by the method of electrochemical anodic dissolution of monocrystalline silicon in a Unno-Imai cell. A mesoporous skin layer with a thickness of about 100-200 nm in the form of cone-shaped nanostructures with pore diameters near 13-25 nm and sizes of skeletal part about 35-40 nm by ion-electron microscopy was observed. The temperature dependence of the relaxation of the most probable relaxation time is characterized by two linear sections with different slope values; the change in the slope character is observed at T approximate to 250 K. The features of the distribution of relaxation times in meso-macroporous silicon at temperatures of 223, 273, and 293 K are revealed. The Havriliak-Negami approach was used for approximation of the relaxation curves epsilon '' = f(nu). The existence of a symmetric distribution of relaxers for all temperatures was found (Cole-Cole model). A discussion of results is provided, taking into account the structure of the studied object.

Automated summary

The dielectric relaxation spectra of macroporous silicon with a mesoporous skin layer in the frequency range of 1-10 Hz were investigated during cooling (up to 173 K) and heating (up to 333 K). The mesoporous skin layer had cone-shaped nanostructures with pore diameters of 13-25 nm, observed by ion-electron microscopy. The temperature dependence of the relaxation time showed two linear sections with a change in slope around 250 K, and a symmetric distribution of relaxers was found for all temperatures using the Cole-Cole model.