Small-diameter silicon nanowire surfaces

Science

Volumn 299, Issue 5614, 2003, Pages 1874-1877

  Ma, D D D ^a   Lee, C S ^a   Au, F C K ^a   Tong, S Y ^a   Lee, S T ^a  

^a CITY UNIVERSITY OF HONG KONG   (Hong Kong)

Author keywords

[No Author keywords available]

Indexed keywords

ENERGY GAP; HYDROFLUORIC ACID; HYDROGEN; OXIDATION; SCANNING TUNNELING MICROSCOPY; SILICON WAFERS; ULTRAHIGH VACUUM; WIRE;

SILICON NANOWIRES (SINW);

NANOTECHNOLOGY;

HYDROFLUORIC ACID; HYDROGEN; NANOPARTICLE; OXIDE; SILICON;

NANOTECHNOLOGY; SILICON;

AMBIENT AIR; ARTICLE; ELECTRIC POTENTIAL; ENERGY; ENVIRONMENTAL TEMPERATURE; IMAGE ANALYSIS; MOLECULAR SIZE; PREDICTION; PRIORITY JOURNAL; QUANTUM CHEMISTRY; QUANTUM MECHANICS; SCANNING TUNNELING MICROSCOPY; STRUCTURE ANALYSIS; SURFACE PROPERTY;

EID: 0037459371     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1080313     Document Type: Article

References (27)

1. A. M. Morales, C. M. Lieber, Science 279, 208 (1998).
2. Y. F. Zhang et al., Appl. Phys. Lett. 72, 1835 (1998).
3. Y. Cui, L. J. Lauhon, M. S. Gudiksen, J. Wang, C. M. Lieber, Appl. Phys. Lett. 78, 2214 (2001).
4. B. Marsen, K. Sattler, Phys. Rev. B 60, 11593 (1999).
5. N. Wang et al., Chem. Phys. Lett. 299, 237 (1999).
6. S. T. Lee et al., J. Mater. Res. 14, 4053 (1999).
7. J. L. Gole, J. D. Stout, W. L. Rauch, Z. L. Wang, Appl. Phys. Lett. 76, 2346 (2000).
8. J. D. Holmes, K, P. Johnston, R. C. Doty, B. A. Korgel, Science 287, 1471 (2000).
9. A. J. Read et al., Phys. Rev. Lett. 69, 1232 (1992).
10. C. Delerue, G. Allan, M. Lannoo, Phys. Rev. B 48, 11024 (1993).
11. B. Delley, E. F. Steigmeier, Appl. Phys. Lett. 67, 2370 (1995).
12. J. B. Xia, K. W. Cheah, Phys. Rev. B 55, 15688 (1997).
13. D. D. D. Ma, C. S. Lee, S. T. Lee, Appl. Phys. Lett. 79, 2468 (2001).
14. Y. Morita, K. Miki, H. Tokumoto, Appl. Phys. Lett. 59, 1347 (1991).
15. G. S. Higashi, Y. J. Chabal, G. W. Trucks, K. Raghavachari, Appl. Phys. Lett. 56, 656 (1990).
16. G. S. Higashi, R. S. Becker, Y. J. Chabal, A. J. Becker, Appl. Phys. Lett. 58, 1656 (1991).
17. M. Niwano, J. Gageyama, K. Kurita, K. Kinashi, I. Takashani, J. Appl. Phys. 76, 2157 (1994).
18. X. H. Sun et al., Inorg. Chem. in press.
19. -10 tort and an air STM (Park Scientific Instruments Autoprobe VP). We obtained all images at room temperature by recording the tip height in real time at a constant tunneling current of 0.3 nA and a bias voltage of 2 V. Electrochemically polished tungsten tips were used. We calibrated the xy piezos for tip scanning within a few percentage points by measuring the atomic image of the HOPG substrate immediately before and after measuring the SiNW. All images presented here have not been processed in any way. Before and after the STS measurement on a wire, measurements were made on the HOPG substrate as references to ensure the reliability of I-V curves. The scanned voltages of all samples except that with the smallest diameter of 1.3 nm (Fig. 3A) were held at less than 2 V. The I-V curves of SiNWs of various diameters were measured at the tip height (about 0.8 nm) where atomically resolved STM images were obtained. A series of I-V curves performed at various tip-to-surface distances centering at 0.8 nm showed that the dI/dV curves and normalized tunneling conductances [(dI/dV)/(I/V)] were relatively insensitive to the tip height, when the tip was set at or close to 0.8 nm. The diameter estimate may be inaccurate because of the uncertain shape of the wire cross section, which has different dimensions along different directions. This is also true for a wire with the faceted cross section shown in Fig. 2, for which the diameter presumably lies between the diameters of an internal cylinder lying within the flat surfaces and an external one touching the edges of the facet boundaries. The STM tine scans of SiNWs indicated near hemispherical profiles with no substantial diameter variation along different directions, in accord with our TEM images showing that the cross section of SiNWs smaller than 20 nm in diameter is more or less round. This is why we estimated the diameter of SiNWs by assuming a circular wire cross section (which in the case of the hexagonal cross section of Fig. 2C would yield an uncertainty of 13%).
20. K. C. Pandey, T. Sakurai, H. D. Hagstrum, Phys. Rev. Lett. 35, 1728 (1975).
21. J. E. Northrup, Phys. Rev. B 44, 1419 (1991).
22. J. A. Stroscio, R. M. Feenstra, A. P. Fein, Phys. Rev. Lett. 57, 2S79 (1986).
23. N. D. Lang, Phys. Rev. B 34, R5947 (1986).
24. R. J. Hamers, Scanning Tunneling Microscopy and Spectroscopy, D. A. Bonnel, Ed. (VCH, New York, 1993), pp. 51-103.
25. R. Q. Zhang et al., unpublished data.
26. L. Pavesi, L. Dal Negro, G. Mazzoleni, G. Franzo, F. Priolo, Nature, 408, 440 (2000).
27. We thank Y. Lifshitz, D. M. Chen, M. Dresselhaus, and G. Dresselhaus for advice, and X. Q. Dai and C. T. Chan for assistance with the graphics. This work is partially supported by a Central Allocation Grant (Project No. CityU 3/01C) and a Competitive Earmarked Research Grant (Project No. CityU 1063/01P) of the Research Grants Council of Hong Kong SAR and by a grant from the Chinese Academy of Sciences, China.