Real- and Q-space travelling: multi-dimensional distribution maps of crystal-lattice strain (∊044) and tilt of suspended monolithic silicon nanowire structures

High-resolution X-ray Bragg diffraction in Al thermomigrated Si channels

Si(111) wafers patterned with an array of vertical 120 µm-wide Al-doped (1 × 1019 cm−3) p-channels extending through the whole wafer were studied with the X-ray double- and triple-crystal diffraction technique in Bragg geometry with copper radiation. Reciprocal space maps (RSMs) of diffraction intensity far from the channels and near them were measured, and their non-trivial shape was observed. The obtained experimental RSMs demonstrate high sensitivity to the structural distortions of the crystal in the subsurface layer owing to the influence of the surface on the elastic strain field in the channel. These features result from the small difference of the ionic radii of Si and Al, leading to the absence of misfit dislocations on the borders of the channel. Simulations of RSMs using the Takagi–Taupin dynamical diffraction theory taking into account the influence of the surface on the elastic strain field in the channel and the effect of the instrumental function were carried out. Finally, numerical RSM calculations showed that the proposed model of the surface effect on the elastic strain field in a semi-infinite crystal with a vertical Si(Al) channel can be used to retrieve the information on the concentration of aluminium in the thermomigrated Si(Al) channel from the diffraction data obtained in the Bragg geometry.

Time-Resolved Nanobeam X-ray Diffraction of a Relaxor Ferroelectric Single Crystal under an Alternating Electric Field

Lead-containing relaxor ferroelectrics show enormous piezoelectric capabilities relating to their heterogeneous structures. Time-resolved nanobeam X-ray diffraction reveals the time and position dependences of the local lattice strain on a relaxor ferroelectric single crystal mechanically vibrating and alternately switching, as well as its polarization under an alternating electric field. The complicated time and position dependences of the Bragg intensity distributions under an alternating electric field demonstrate that nanodomains with the various lattice constants and orientations exhibiting different electric field responses exist in the measured local area, as the translation symmetry breaks to the microscale. The dynamic motion of nanodomains in the heterogeneous structure, with widely distributed local lattice strain, enables enormous piezoelectric lattice strain and fatigue-free ferroelectric polarization switching.