Ferroelectric nanodomains were created in Ba0.8Sr0.2TiO3 (BST 80/20) thin films by applying a voltage to a sharp conducting tip of a scanning probe microscope (SPM). The ferroelectric layer were grown on (100)-oriented silicon substrate by radio frequency magnetron sputtering. The surface of the sample shows small grains which diameter ranges from 50 nm to 75 nm and roughness is less than 5 nm. Using the piezoresponse mode of the SPM to detect the out-ofplane film polarization, the domain sizes were measured as a function of the applied writing voltage and the pulse time. It was found that the time dependence of the domain diameter in a 400 nm thick BST 80/20 film well described by logarithmic law observed earlier in Pb(Zr0.2Ti0.8)O3 (PZT) films. The dynamics of domain growth is analyzed theoretically taking into account the strong inhomogeneity of the external electric field in the film and the influence of the bottom electrode. Therefore, the BTS film with good polarization switching properties could act as a memory element in nonvolatile ferroelectric random access memory (NV-FRAM) devices.
Transformation of microstructure of the buried He bubbles of silicon surface layer after He+ low energy plasma immersion ion implantation and subsequent low-thermal annealing were studied by high resolution X-ray diffraction and reflectivity, Rutherford backscattering spectroscopy, transmission electron and atomic force microscopy methods. The ion energies varied in the range 2 – 5 keV at constant exposure ion doses 5×·1017 cm-2. Formation of a three-layer structure (amorphous a-SiOx layer at the surface, amorphous a-Si layer with helium bubbles and buried helium bubbles heavy damaged tensile strained crystalline c-Si layer) that is retained after annealing was observed. Helium-filled bubbles are observed in an as-implanted sample. Evolution of the multilayer structure and the bubbles due to annealing are revealed and comparing with the structural parameters of an as-implanted sample was done. The bubbles are shown to trend into two-model distribution after annealing. The characteristic bubble size is determined to be in a range of 2–20 nm. Large size helium-filled bubbles are located in the amorphous a-Si layer. Small size bubbles are revealed inside the damaged crystalline Si layer. These bubbles are a major source of tensile strain in c-Si layer.
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