|
A monolayer of inorganic nanoparticles was fabricated on a Silicon wafer using a cage- shaped protein, ferritin, which can sequester several types of inorganic nanoparticles in their cavities. Ferritins were bound electrostatically in an aqueous condition to the silicon wafer, which was modified with aminosilane molecules. We have used X-ray photoelectron spectroscopy (XPS) to study the effects of ion bombardment on a freshly cleaned ferritin surface. Compositional changes induced by 3.0 keV Ar+ sputtering in Fe2O3-ferritin nanoparticles have been quantitatively studied by XPS. All the Fe2O3-ferritin nanoparticles showed important changes to Fe nanoparticles in their stoichiometry for 30 sec with Ar+ sputtering. Further more, Kelvin force microscopy (KFM) in high vacuum has shown that there exists a very high surface potential, probably owing to the reduction of the surface to its element induced by Ar+ ion bombardment. With regard to the origin of the surface reduction of activities, the induced surface potential is discussed. Compositional changes induced by Ar+ bombardment of Fe2O3, have been quantitatively characterized by XPS. Fe2O3 resolves into two elements, which are Fe and oxide. From the present studies of the ion bombardment reaction of Fe2O3 to the type of Fe pure metals, we found new information about on its mechanisms: It has been suggested that the surface potentials measured using KFM in high vacuum may be induced by the metal oxide and metal surfaces without contamination layers appearing with increasing ion bombardment activity, which relate closely to surface atomic displacement excited by Ar+ ion bombardment. In this paper, we present a comparative study of the compositional changes induced by 3.0 keV Ar+ in Fe2O3 with XPS and KFM without contamination layer in high vacuum. We performed surface measurements by a KFM in high vacuum to find the difference in work function between Fe2O3 and Fe, which might be correspond to the particles of metal oxidation and pure metal observed by KFM in high vacuum. We hope that this work not only demonstrates the experimental success of the fusion of biology and Si device processing but also opens the door to the biological path to the nano-electronic devices. |