Ge Quantum Dots On Si Surface Mbe Epitaxial Growth And Its Structural Characterization

Due to the quantum confinement effect, the Ge quantum dots (QDs), grown by self-assembly, show many novel optoelectronic properties. The devices utilizing these properties may be potentially used in the future integrated-chip circuit and nanoelectronics. In this thesis, by using the Si electron beam evaporator (EBE) and UHV MBE system which are developed and set up by ourselves, a flat and crystalline Si epitaxial film has been obtained on Si substrate. On the surface of Si buffer layer and thin SiO₂/Si film, the Ge QDs with high density and small size have been fabricated by optimizing the growth parameters. AFM and RHEED observations have been performed to study the morphology, growth process and crystalline quality of Si film and QDs. PL and EXAFS measurements have been used to study the local structure and optical property of QDs, respectively. The major results are listed as follows:1. The setup of MBE system and development of electron beam evaporatorAn UHV MBE system has been set up for the fabrication of Ge QDs and a Si electron beam evaporator (EBE) has been developed successfully by us. Because of the special cantilever design, the Si EBE has avoided the high-voltage discharge and electrode short completely, and it has many advantages, such as simple structure, low price, easy maintenance, etc. It has been applied successfully to the homoepitaxial growth of Si crystalline film.2. The chemical cleaning of Si surface and the homoepitaxy growth of crystalline Si filmA moderate, simple and effective chemical cleaning method for Si surface has been improved successfully. The Si(001) surface, which is cleaned by this chemical method and then degassed at 650℃, shows a (2×1) reconstruction surface. By using the Si EBE, the crystalline Si film has been grown on this cleaned Si surface...