NANOYAPILI İNCE FİLM ÖRNEKLERİN, GEÇİRMELİ VE YÜZEY TARAMALI X-IŞINI SAÇILMA YÖNTEMLERİ (SAXS-GISAXS) İLE İNCELENMESİ
Özet
In this thesis, SAXS (Small Angle X-ray Scattering) and GISAXS (Grazing Incidence Small Angle X-ray Scattering) methods were used to analyze 3D nano scale structures of the crystalline, amorphous and polymer thin films. A high flux modern laboratory type GISAXS system which was produced in Anton Paar's R&D laboratory was utilized for the GISAXS measurements. Thus, the thin film structures were not only examined in the X-ray transmission mode by the SAXS method but also the detailed and more realistic analyzes were carried out by scanning the surfaces and descending to the surface depth with GISAXS method. In these researches, several single and multilayer thin films fabricated by expert scientists at Hacettepe University and Gazi University have been analyzed. Therefore, in this thesis study, power of X-ray scattering techniques, namely SAXS and GISAXS, for providing detailed structral information from nanostructured thin films have been investigateed in three structrally distinct sample sets.
In the first group, Ge nanoparticles embedded multilayered ZnO thin film samples prepared by sequential magnetron sputter technique were investigated in two groups as Rapid Thermal Annealed (RTA) and untreated (Asmade) samples. The effect of different O2 partial pressures (1, 3 and 5 mTorr) utilized during ZnO growth were investigated. It has been realized that especially, increasing pressure induces orthogonal like prismatic morphology at 1 mTorr, cylindrical at 3 mTorr and more compact spherical formation at 5 mTorr. Such that, it has been understood that, pronounced morphology control at nano scale can be achieved by changing the O2 partial pressure for the oxide matrices.
In the second group, "hydrogenated nanocrystalline silicon suboxide" (nc-SiOx: H; x <1) thin film samples prepared by hydrogen dilution at different ratios (99%, 95%, 90%) in plasma enhanced chemical vapor deposition system (PECVD) were investigated. It has been found that K23 and K28 coded samples with a 90% hydrogen dilution ratio have highly uniform distribution of core-shell nano aggregations while K15 coded thin film with a 95% hydrogen dilution ratio has nano-scale fractal formations. The similar nano formations have been also seen in the hydrogenated amorphous silicon suboxide multilayer CKSiOx8 coded thin film. The physical parameters of the second group samples expressed in different codes were also given in the scope of the thesis. As a result of the study for this group it may be said that morphologies, sizes and distributions of the nano aggregations can be taken under control by the hydrogenation.
Thin films of the third group were gold nanocrystall and Parylene-C (PPX) thin films. It was obtained that Parylene-C films, which have superior electrical stability and insulating properties and commercial preservation, have different nanoformations and structural morphologies at the end of the applied conventional vapor deposition and oblique angle vapor deposition methods. Differences in the morphology and distribution of 3D nano-forming fractal clusters have been identified as a result of the vapor deposition method on different substrate of these single-layer films exhibiting fractal formations in poly core shell morphology with variable radius. Directionally oriented growth directions of gold nanocrystalline thin films obtained by oblique angle deposition method were also determined.
As a result of the present study, morphologies, physical dimensions, sizes, distance distributions, the most possible (ab-inito) 3D formations of the nano aggregations have been acquired in electron density level.
As a general result of the study, it has been clearly understood the obtained nano structural information is much more precise and accurate in GISAXS analysis with respect to that of SAXS analyses. So, it should be noted that high flux X-ray sources must be used for the nanostructral investigations of thin films.
