Modification of Semiconductor Surface Properties with Chemically Bound MolecularFilms

摘要

In line with these objectives three parallel and connected thrusts were pursued:(1) investigation of the use of Langmuir-Blodgett (LB) films in MIS Schottky structures to modify the barrier properties of junctions made from SiO2/Si and GaAs(100), (2) the treatment of Si and GaAs(100) surfaces with inorganic P and S compounds in order to favorably modify the electrical behavior, primarily via passivation of surface traps, and (3) the development of self-assembled monolayers of organothiols, in particular, alkanethiolates on GaAs(100) as a means to modify the electrical properties of the surface and more recently as a new class of ultrahigh resolution lithographic resists for nanofabrication. In support of each of these thrusts extensive work was carried out in two areas: characterization of the structure and composition of the surface films, primarily by infrared spectroscopy (IRS), x-ray photoelectron spectroscopy (XPS) and ellipsometry and characterization of the electrical behavior of the film and its interface with the semiconductor, primarily by fabrication of MIS Schottky diode structures and measurement of I-V and C-V response, but also including limited photoluminescence and photoreflectance measurements. All the work was directed ultimately for the chemically bonded molecular film samples. The LB films represented molecules adsorbed with no chemical bonding, the inorganic treatments represented chemically modified surfaces with molecular groups and the chemically bound inorganic films contained both the previous aspects. Semiconductors, Molecular films, Langmuir-Blodgett films, Organothiols, Surface films, Schottky diode structures.