DECOMPOSITION OF B2H6 ON NI(100)

The decomposition of diborane (B2H6) has been studied on the Ni(100) s urface by means of thermal desorption spectrometry (TDS), x-ray photoe lectron spectroscopy (XPS), and low-energy electron diffraction (LEED) . At low gas exposures, decomposed B2H6 on the Ni(100) surface at low temperatures produces several peaks in the H-2 TDS spectra. At high ga s exposures, B4H10 was observed desorbing from the surface. The TDS sp ectra and XPS results for low gas exposures indicate that heating to 5 00 K results in complete decomposition of B2H6, leaving B bonded to th e Ni(100) surface. Heating a thick boron film to 700 K results in a si gnificant shift in the B [1s] and Ni [2p(3/2)] XPS peak positions, ind icating that adsorbed B reacts with Ni(100) to form a nickel boride ph ase. This nickel boride phase is stable on the surface at temperatures up to 900 K. Nickel boride standards (NiB, Ni2B, Ni3B) were used for comparison with the surface nickel boride phase. XPS analysis of the s tandards led to the determination that the phase forming on the surfac e at 700 K was Ni2B. As the temperature is increased above 900 K, XPS results indicate that the boron diffuses rapidly into the bulk. It has also been found that high-temperature annealing in the presence of B2 H6 results in the formation of a sharp (3x3) LEED pattern produced by 2/9 ML of B on the Ni(100) surface. (C) 1997 American Vacuum Society.