Alloy Thin Films from Discrete Metallaborane Clusters

Abstract

ABSTRACTThe ferraborane HFe4 (CO)12 BH2 sublimes at 50 °C and decomposes by loss of H2 and CO on various substrate surfaces at 160–180 °C to yield films having metallic appearances with typical thicknesses of 4000Å. These films are amorphous by X-ray, conduct electricity and adhere well to glass, metal and silicon substrates. The composition was determined by ESCA and Auger spectroscopies. The films exhibit highly uniform composition and the Fe/B ratio is 4 showing that film stoichiometry is defined by the cluster core. The ESCA chemical shifts show the presence of boride and metallic iron. At present the bulk film contains a high level of oxygen in the form of iron and boron oxides. No ax-iron is present by X-ray or Mössbauer spectroscopies. Some carbon and hydrogen (SIMS) are present. Mössbauer spectra show the presence of magnetic iron similar to that exhibited by authentic Fe80 B20 samples but the films also contain substantial paramagnetic iron.