Adsorption of boron on a Mo(110) surface

Abstract

Adsorption of boron atoms in submonolayer to multilayer coverage on atomicallyclean Mo(110) surfaces has been studied by Auger electron spectroscopy (AES),x-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy(EELS) and work function measurements. According to Auger results there is alayer-by-layer growth mode of the film on the substrate held at room temperature.In the submonolayer region the work function gradually increases with boroncoverage until a saturation value of 5.8 eV is achieved after completion of the firstmonoatomic layer. The B–Mo(110) adsorbate system formed on the substrate at roomtemperature is not stable, dominated by a strong tendency of the boron atoms todiffuse into the bulk of the crystal. The latter is manifested by dramatic Mo(110)surface plasmon mode transformation upon boron adsorption, presumably as aresult of penetration of boron atoms into the topmost substrate layer even atT = 300 K. Slight annealing up to 450 K facilitates this trend, leading to total dissolution ofdeposited boron atoms in the bulk of the crystal under further annealing, restoring theinitial state of the Mo(110) surface after achieving a temperature of approximately 2000 K.