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Bi-Te nanoplates (NPs) grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and Auger electron spectroscopy (AES). We find that the surface of relatively thick (more than tens of nanometers) Bi2Te3 NPs is oxidized in the air and forms a bump under heating with moderate laser power, as revealed by the emergence of Raman lines characteristic of Bi2O3 and TeO2 and characterization by AFM and EDS. Further increase of laser power burns holes on the surface of the NPs. Thin (thicknesses less than 20 nm) NPs with stoichiometry different from Bi2Te3 were also studied. Raman lines from non-stoichiometric NPs are different from those of stoichiometric ones and display characteristic changes with the increase of Bi concentration. Thin NPs with the same thickness but different stoichiometries show different color contrast compared to the substrate in the optical image. This indicates that the optical absorption coefficient in thin Bi-Te NPs strongly depends on their stoichiometry.

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Publication history

Received: 01 July 2014
Revised: 11 August 2014
Accepted: 18 August 2014
Published: 27 September 2014
Issue date: March 2015

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© Tsinghua University Press and Springer-Verlag Heidelberg 2014

Acknowledgements

Acknowledgements

Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund (No. 53401-UNI10) for support of this research. S. S. thanks Wayne Jennings for his assistance with the AES measurements. R. H. acknowledges support from UNI Faculty Summer Fellowship. T. E. K. acknowledges support by NSF RUI Grant (No. DMR-1206530) and a UNI capacity building grant. R. H. and T. E. K. both acknowledge the support by NSF RUI Grant (No. DMR-1410496). X. P. A. G. acknowledges the NSF CAREER Award program (No. DMR-1151534) for support of research at CWRU.

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Email: nanores@tup.tsinghua.edu.cn

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