Manganese nanoclusters and MnSi∼1.7 nanowires formed on Si(110): A comparative x-ray photoelectron spectroscopy study

• Published in: Journal of applied physics 2013-01, Vol.113 (2)
• Main Authors: Zou, Zhi-Qiang, Shi, Gao-Ming, Sun, Li-Min, Liu, Xiao-Yong
• Format: Article
• Language: English
• Subjects: ATOMIC CLUSTERS; BINDING ENERGY; Clusters; CRYSTAL GROWTH; LAYERS; MANGANESE; MANGANESE ALLOYS; MANGANESE COMPOUNDS; MATERIALS SCIENCE; Nanostructure; Nanowires; OXIDATION; Oxidation resistance; QUANTUM WIRES; SCANNING TUNNELING MICROSCOPY; SILICIDES; SILICON ALLOYS; SILICON OXIDES; SPECTRA; SURFACES; TEMPERATURE RANGE 0273-0400 K; TUNNEL EFFECT; X-RAY PHOTOELECTRON SPECTROSCOPY
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4774098

The growth of Mn on a Si(110) surface at room temperature (RT) and 550 °C has been investigated by scanning tunneling spectroscopy (STM) and X-ray photoelectron spectroscopy (XPS). STM observation shows that the growth at 550 °C results in the formation of nanowires (NWs), while that at RT produces only nanoclusters. The Mn 2p XPS spectra unambiguously reveal that the NWs are composed of MnSi∼1.7 and the nanoclusters are composed of Mn. Curve-fitting analysis of the spectra shows that 64.9% of the NWs were oxidized due to atmospheric exposure during sample transfer, while the Mn nanoclusters were completely oxidized under the same conditions. This fact indicates that the MnSi∼1.7 NWs have better oxidation resistance than the Mn clusters, which can be attributed to the protection effect of the SiO2 layer formed on the NWs and the smaller surface to volume ratio of the NWs comparing with the clusters. The binding energy of Mn 2p for the NWs exhibits a negative shift of ∼0.5 eV with respect to the Mn metallic state, which is similar to the silicide state of earlier transition metals Ti and Cr, but different from that of later transition metals Fe and Ni. This negative shift can be attributed to the contribution of Madelung potential.