| Novel Z-contrast imaging technique in combination with electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) in the scanning transmission electron microscope are applied to study various semiconductor nanostructures. The theoretical background and practical issues of using Z-contrast imaging, EELS and EDS for semiconductor nanostructure research, as well as some TEM specimen parameters, including specimen preparation, contamination and beam damage are discussed.; A comprehensive study of the source/drain regions and subnanometer gate oxide in Si based metal oxide semiconductor field effect transistors (MOSFET) was performed. Arsenic segregation with a very narrow profile occuring precisely at the Si/silicide interface was identified. A detailed low loss EELS analysis of the arsenic doped and undoped devices reveal that arsenic remains electrically active and supplies additional charge carriers at the interface. These results are consistent with the electrical measurements showing a decrease in contact resistance for the transistors. For the gate oxide, the existence of the inhomogeneous local strain field at the Si/SiO2 interface was identified and qualitatively characterized. EELS analysis provided information on the spatial extent of the suboxides, dielectric properties and leakage current.; The study of (Cd,Mn,Zn)Se/(Zn,Mn)Se, In(Sb,As), and (In,Ga)Sb based semiconductor quantum dot (QD) systems provided valuable information on the individual QD parameters as well as the ensemble statistical characteristics. Different modes of internal compositional modulations on the atomic and nanometer length scales for the QDs in these material systems revealed in the study may constitute new types of QDs. These modulations are discussed as having arisen from a structural response to a combination of internal and external strains in QDs. Thermal treatments of (Cd,Mn,Zn)Se/(Zn,Mn)Se based heterostructures inside the electron microscope resulted in the formation of three-dimensional CdSe rich QDs from (quasi-)two-dimensional (2D) CdSe rich platelets. Statistical characteristics of the latter QD ensemble was found to be by superior to that of CdSe based as grown QDs. A discussion of the long-term stability of the QDs is also provided. |
