I. Isolation of LAC Operator DNA. II. XPS Investigation of the GaAs/Native Oxide and Si/Metal Interfaces

Chapter I A procedure is presented for the large scale isolation of cloned 29 base-pair lac operator DNA from plasmid DNA. The methodology is general and may be used to isolate other cloned DNA fragments as well. Initial ultraviolet difference experiments with lac repressor protein are also presented. Solvent perturbation is used to locate the tyrosine and tryptophan residues. Chapter II The chemical structure of the thin native oxide of GaAs (30 - 40 Å) has been investigated using x-ray photoelectron spectroscopy. Both wet chemical and argon ion bombardment techniques have been used to depth profile the oxide structure. The composition of the oxide is found to be quite complex and the distribution of the various species as a function of oxide thickness is discussed. A Fouries transform data reduction technique based on linear prediction has been used to develop possible explanations for the experimentally observed chemical shifts and composition layers. Evidence is found for the presence of As2O3, Ga2O3, and the mixed oxide GaAsO4. Chapter III A systematic investigation of the bonding properties of selected transition metal silicides on single crystal Si substrates is proposed. 4He+ back scattering, XPS, and x-ray excited AES will be used to characterize both the bulk and interfacial bonding properties. Initial experiments are presented to demonstrate the feasibility of the approach.