Abstract
A scanning tunneling microscope (STM) was used to fabricate T-phase tantalum diselenide (TaSe 2 ) nanocrystals with sizes ranging from 7 to more than 100 nanometers within the surface layer of 2H-TaSe 2 crystals at liquid helium temperature. Atomic-resolution images elucidate the structural changes between T- and H-phase regions and were used to develop an atomic model that describes a pathway for the production of T-phase nanocrystals from the H-phase crystal precursor through a solid-solid phase transition. The size-dependent properties of these nanocrystals may lead to improved understanding of the physics of charge density waves in small structures.
References
27
Referenced
64
10.1038/344524a0
-
Whitman L. J., Stroscio J. A., Dragoset R. A., Celotta R. J., Science 25112061991.
(
10.1126/science.251.4998.1206
) / Science by Whitman L. J. (1991) - Lyo I.-W., Avouris Ph., ibid. 2531731991. / ibid. by Lyo I.-W. (1991)
- Jung T. A., Schlittler R. R., Gimzewski J. K., Tang H., Joachim C., ibid. 2711811996. / ibid. by Jung T. A. (1996)
10.1038/363524a0
10.1126/science.264.5161.942
-
Dagata J. A., et al., Appl. Phys. Lett. 5620011990; E. A. Dobisz and C. R. K. Marrian, ibid.58, 2526 (1991).
(
10.1063/1.102999
) / Appl. Phys. Lett. by Dagata J. A. (1990) 10.1126/science.262.5137.1249
-
Snow E. S., Campbell P. M., Science 27016391995.
(
10.1126/science.270.5242.1639
) / Science by Snow E. S. (1995) - Sheehan P. E., Lieber C. M., ibid. 27211581996. / ibid. by Sheehan P. E. (1996)
-
Wilson J. A., DiSalvo F. J., Mahajan S., Adv. Phys. 241171975.
(
10.1080/00018737500101391
) / Adv. Phys. by Wilson J. A. (1975) - Coleman R. V., et al., ibid. 375591988. / ibid. by Coleman R. V. (1988)
- In the modification procedure we used several methods. In one the feedback loop was opened the tip was advanced a preset amount toward the surface and then the bias voltage was pulsed or ramped to the desired value. Alternatively we allowed the z-loop to oscillate (by increasing the gain) for a short time (≤100 ms) at the desired voltage value. We were able to create controlled T-phase nanocrystals using both of these methods.
- The success probability depends on the magnitude of the applied bias voltage and the tip and tunneling junction conditions. At bias voltages exceeding ∼1.8 V the success probability for nanocrystal formation is on the order of 90%; this probability drops to zero at the modification threshold voltage ∼1.2 V. These values exhibit uncertainty that reflects variations in tip structure and junction conditions.
- The model in Fig. 3 A illustrates the motion of Se atoms in response to a repulsive force that is expected when a negative bias voltage is applied to the STM tip. The Se atom vacancies predicted by our model (with a negative bias) have not yet been observed although they are expected to be difficult to detect for several reasons. First the percentage of vacancies is small; we estimated <1% vacancies in a single 40-nm T-phase crystal. Second it is intrinsically difficult to observe all of the atomic sites in T-phase single crystals or nanocrystals because of the strong CDW modulation. In addition this same model predicts that Se adatoms would be produced when a positive bias voltage was used to drive the transformation (because the Se atom motion would be toward the tip). The small number of adatoms generated in this reverse direction will not be readily observed because they would be expected to exhibit significant mobility on the surface.
- The experimental data (Fig. 3 C) show that the Se atoms at the interface form a rectangular cell that is only slightly distorted from a square and thus these results contrast with the rectangular model cell suggested by Fig. 3B. The difference between the experimental results and the model is believed to be due to relaxation of the Se atom positions at the interface between the T- and H-phases.
- These bias voltage--dependent modification experiments were carried out at similar tip-sample separations with electrochemically etched Ir tips. Because the etched Ir tips yield relatively reproducible bias-dependent modifications which suggest that their shapes are similar we believe that the major effect of these experiments is a variation in the electric field (which also depends on both the tip-sample separation and the tip shape).
-
Persson B. N. J., Demuth J. E., Solid State Commun. 577691986.
(
10.1016/0038-1098(86)90856-2
) / Solid State Commun. by Persson B. N. J. (1986) 10.1126/science.254.5036.1319
-
Persson B. N., Avouris Ph., Chem. Phys. Lett. 2424831995.
(
10.1016/0009-2614(95)00778-3
) / Chem. Phys. Lett. by Persson B. N. (1995) -
Sato A., Tsukamoto Y., Nature 3634311993.
(
10.1038/363431a0
) / Nature by Sato A. (1993) -
Staufer U., et al., J. Vac. Sci. Technol. A65371988.
(
10.1116/1.575377
) / J. Vac. Sci. Technol. by Staufer U. (1988) -
Lieth R. M. A., Terhell J. C. J. M., Preparation and Crystal Growth of Materials with Layered Structures, Lieth R. M. A.ReidelBoston1977141--223.
(
10.1007/978-94-017-2750-1_4
) / Preparation and Crystal Growth of Materials with Layered Structures by Lieth R. M. A. (1977) - Peierls R. E., Quantum Theory of SolidsOxford Univ. PressOxford1955108; H. Fröhlich, Proc. R. Soc. London Ser. A223, 296 (1954). / Quantum Theory of Solids by Peierls R. E. (1955)
10.1126/science.271.5251.933
- The reported CDW wavelength dispersions correspond to the standard deviation calculated from experimental images. We digitized the images to locate the CDW maxima and then we used the distances between adjacent maxima to calculate the average and uncertainty in wavelength. The observed experimental uncertainty in roughly infinite crystals was 0.6 Å.
- We thank E. Kaxiras and F. Spaepen for helpful discussions. The work of C.M.L. was supported under NSF award DMR-9306684.
Dates
Type | When |
---|---|
Created | 23 years ago (July 27, 2002, 5:39 a.m.) |
Deposited | 1 year ago (Aug. 7, 2024, 7:29 a.m.) |
Indexed | 3 weeks, 5 days ago (July 26, 2025, 4:45 a.m.) |
Issued | 28 years, 9 months ago (Nov. 1, 1996) |
Published | 28 years, 9 months ago (Nov. 1, 1996) |
Published Print | 28 years, 9 months ago (Nov. 1, 1996) |
@article{Zhang_1996, title={Creation of Nanocrystals Through a Solid-Solid Phase Transition Induced by an STM Tip}, volume={274}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.274.5288.757}, DOI={10.1126/science.274.5288.757}, number={5288}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Zhang, Jian and Liu, Jie and Huang, Jin Lin and Kim, Philip and Lieber, Charles M.}, year={1996}, month=nov, pages={757–760} }