.ge / Si And Tin / Si <sub> 3 </ Sub> N <sub> 4 </ Sub> Surfaces And Interfaces Of The Low-dimensional Systems

In this thesis, the Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscope (AFM), high resolution Transmission Electron Microscope (HR-TEM), Raman spectrum, X-ray Diffraction (XRD) and Fluorescence X-ray absorption fine structure (XAFS) have been synthetically used to study the local structures as well as the surface and interface effects of IV-IV semiconductors Ge-Si/Si(001) system and TiN/Si₃N₄ super-hard multilayer films. At first, the thickness, modality of Ge layer and local structures of IV-IV semiconductors hetero-structural films were investigated by RHEED and grazing incidence fluorescence XAFS. The composition and the structural parameters such as tetragonal unit cell distortion were accurately determined for the two-dimensional quantum semiconductors with diamond structure. The surface and interface effects of Ge layer and Ge-Si interlayer were analyzed in detail. Subsequently, the modality, optic characteristic and local structure of zero-dimensional quantum dots were studied through combining with AFM, HR-TEM Raman spectrum and XAFS techniques. Above investigation is useful to understand the formation mechanism of quantum structure in the Ge-Si quantum semiconductor system more reliably and straightforwardly and will provide new information on the design and fabrication of such system. Finally, XRD and Fluorescence XAFS were used to study the long order and local structure as well as the interface effect of TiN/Si₃N₄ super-hard multilayer films. The analysis on the intrinsic relationship between structure and performance will provide the structure foundation for explaining the hardness enhancement mechanism for TiN/Si₃N₄ super-hard multilayer films. The main content in this thesis is as follows:1. Ge/Si quantum systemThe RHEED and grazing incidence fluorescence XAFS has been used to study the thickness, modality of Ge layer and local structure of Ge_n/Si(001) (n=1, 2 and 4 monolayer, ML) overlayer and Si/Ge_n/Si(001) (n=1, 2, 4 and 8 ML) heterostructural films grown by MBE at 400℃. We investigated the interaction between Ge and Si atoms during the overgrowth of Si layer and discussed the possible mechanism of Ge-Si interface effect. The XAFS results indicate that there is a strong Ge migration effect in all Si/Gen/Si(001) heterostructural films and the length of migration is considerable. For the 1 or 2 monolayer (ML) Ge heterostructural film, the Ge atoms are dominantly surrounded by Si, and the Ge layers are completely consumed to form SiGe alloy. With the thickness of the Ge monolayer increasing to 4 ML, the determined Si/Ge coordination numbers (N_Ge-Si:N_Ge-Ge=2.7:1.3) is similar to that of Si_0.70Ge_0.30 alloy, and there are about 2.0 ML Ge atoms mixing with the Si capping layer. Even for the 8-ML-thick Ge heterostructural film, the fraction of Ge-Ge coordination pair in the first shell is about 55%, close to that in Si0.50Ge0.50 alloy. It means that about 3.0 nominal ML Ge atoms in Si/Ge₈/Si(001) heterostructural film migrate into the Si capping layer to form a Ge-Si alloy. We suggest the migration mechanism of...