| Abstract
| - Adsorption and thermal decomposition of trimethylphosphine (PMe3) and triethylphosphine (PEt3) on theCu(110) surface are investigated using temperature-programmed desorption (TPD) and X-ray photoemissionspectroscopy (XPS) with synchrotron radiation. Both PMe3 and PEt3 chemisorb molecularly on three adsorptionsites on a Cu(110) surface at 100 K and are mostly desorbed intact upon annealing to 520 K. However, afraction of chemisorbed PMe3 and PEt3 undergoes decomposition via dealkylation. Chemisorbed PEt3 undergoesthermal decomposition to a greater extent than PMe3. PMe3 molecules decompose thermally to form surfaceCH3 and phosphorus through PMe2 as an intermediate. Surface CH3 eventually disproportionates to formCH4 and surface carbon at a temperature above 420 K. Chemisorbed PEt3 molecules undergo stepwisedeethylation (PEt3 → PEt2 → PEt → P), resulting in surface C2H5 and phosphorus; the surface C2H5 moietyfurther decomposes to evolve C2H4 and H2 through β-hydride elimination. Hence a Cu film grown from aCVD precursor containing PEt3 ligands is almost free of carbon, but however, may be deposited with ahigher concentration of phosphorus, relative to PMe3.
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