Cel
The main aim of the Proposal is the creation of new approaches in the X-ray diagnostics of thin films and complex heterocompositions used in micro- and nano-electronics.
The scientific aims are:
(1) Development of adequate procedures for fitting the experimental rocking curves within the developed models using a large number of experimental points (up to 104) and fitting parameters (up to 100) and taking accurately into account the errors contained in the experimental data;
(2) Theoretical and experimental study of the processes of wave-field formation and the yield of secondary radiations (photoelectrons, fluorescent radiation) under the conditions of X-ray diffraction by heterostructures with nanometer layers including quantum wells, quantum wires and quantum dots as well as -layers;
(3) Unambiguous restoration of the depth profiles of structural distortions in heterostructures and crystals with extended distorted (by diffusion, epitaxy, ion implantation) subsurface layers using the data obtained by the methods of X-ray diffraction and X-ray standing waves;
(4) Design of a new method of investigation of ultra-thin (of the order of 1 nm) surface layers based on the analysis of a specularly reflected wave formed under the conditions of grazing incidence non-coplanar X-ray diffraction.
The Proposal includes the following research activities:
- theoretical and experimental studies of X-ray diffraction scattering and the yield of secondary radiations (photoelectrons, fluorescent radiation) from multilayer nanostructures in different diffraction geometries;
- creation of an adequate procedure for fitting the experimental rocking curves with due regard for all possible experimental errors and the determination of the structural parameters (lattice strain and disordering, thickness) of individual layers and interfaces;
- measurements of triple-crystal X-ray diffractometry spectra with the aim to separate the diffuse scattering from defects;
- measurements of high-resolution X-ray diffraction spectra for multilayer structures in the grazing and asymmetric diffraction schemes;
- characterisation of the process of strain relaxation in multilayer heterostructures by reciprocal space mapping;
- energy-dispersive measurements of the yield of photoelectrons in the framework of the X-ray standing-wave method for the direct phase analysis;
- combined processing triple-crystal X-ray diffractometry spectra and curves of photoelectron yield for the unambiguous determination of depth profiles of lattice strain and disordering in the subsurface layers located at various depths in a crystal;
- theoretical description of the generation of specularly reflected waves under the conditions of non-coplanar X-ray diffraction and analysis of its sensitivity to ultra-thin amorphous and crystalline surface films;
- measurements of the specularly reflected waves under the conditions of the non-coplanar X-ray diffraction at relatively large angles of X-ray incidence onto perfect crystals and specimens with disturbed nanometer-thick layers;
- independent inspection (electron microscopy, Auger spectroscopy) of a reliability of the outcomes obtained by new offered x-ray diffraction methods.
Thus, the Proposal envisages the development of new quantitative methods for characterisation of ultra-thin films and multilayer nanostructures having no analogues with respect to their precision, space resolution, and reliability, which is rather essential for optimisation of technological parameters of growth of the heterostructures involved in concrete microelectronic devises.
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43010 Parma
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