_{2}nanowire contacts

^{1,a)}and Juhn-Jong Lin

^{1,2,b)}

### Abstract

A good understanding of the electronic conduction processes through nanocontacts is a crucial step for the implementation of functional nanoelectronic devices. We have studied the current- voltage () characteristics of nanocontacts between single metallic nanowires and contacting Auelectrodes, which were pre-patterned by simple photolithography. Both the temperature behavior of contact resistance in the low-bias voltage ohmic regime and the curves in the high-bias voltage non-ohmic regime have been investigated. We found that the electronic conduction processes in the wide temperature interval 1-300 K can be well described by the fluctuation-induced tunneling (FIT) conduction theory. Taken together with our previous work [Lin *et al.*, Nanotechnology **19,** 365201 (2008)], where the nanocontacts were fabricated by delicate electron-beam lithography, our study demonstrates the general validity of the FIT model in characterizing electronic nanocontacts.

The authors are grateful to F. R. Chen and J. J. Kai for providing us with the NWs used in this study and for P. Sheng and H. Xie for valuable discussions. This work was supported by the Taiwan National Science Council through Grant No. NSC 99-2120- M-009-001 and by the MOE ATU Program.

I. INTRODUCTION

II. EXPERIMENTAL METHOD

III. RESULTS AND DISCUSSION

IV. CONCLUSION

### Key Topics

- Nanocontacts
- 19.0
- Electrodes
- 12.0
- Gold
- 12.0
- Temperature measurement
- 8.0
- Contact resistance
- 7.0

## Figures

(Color online) (a) Current-voltage curves at 1.6, 15, 30, 45, 60, 90, and 300 K for device A. The inset shows an expanded plot for the *I-V* curve at 1.6 K. (b) A schematic of a contacting Au electrode pair bridged with a single NW. The NW is directly placed on the surfaces of the Au electrodes. (c) An SEM image of device A. The scale bar is 2 *μ*m.

(Color online) (a) Current-voltage curves at 1.6, 15, 30, 45, 60, 90, and 300 K for device A. The inset shows an expanded plot for the *I-V* curve at 1.6 K. (b) A schematic of a contacting Au electrode pair bridged with a single NW. The NW is directly placed on the surfaces of the Au electrodes. (c) An SEM image of device A. The scale bar is 2 *μ*m.

(Color online) Zero-bias resistance as a function of temperature for two NW devices, as indicated. The symbols are the experimental data. The solid curves are the least-squares fits to Eq. (1). The dashed curves are the theoretical predictions of the same equation but are plotted by directly substituting the and values extracted from (Eq. (5)). For clarity, the data for the device B have been shifted up by multiplying a factor of 2.

(Color online) Zero-bias resistance as a function of temperature for two NW devices, as indicated. The symbols are the experimental data. The solid curves are the least-squares fits to Eq. (1). The dashed curves are the theoretical predictions of the same equation but are plotted by directly substituting the and values extracted from (Eq. (5)). For clarity, the data for the device B have been shifted up by multiplying a factor of 2.

(Color online) Current-voltage characteristics at high bias voltages for (a) device A and (b) device B at several temperatures, as indicated. The symbols are the experimental data. The solid curves are the least-squares fits to Eq. (4).

(Color online) Current-voltage characteristics at high bias voltages for (a) device A and (b) device B at several temperatures, as indicated. The symbols are the experimental data. The solid curves are the least-squares fits to Eq. (4).

(Color online) The parameter *a* in Eq. (4) as a function of temperature for devices A and B, as indicated. The solid curves are the least-squares fits to Eq. (5). The dashed curves are the theoretical predictions of the same equation, but plotted by directly substituting the and values extracted from the fits to Eq. (1).

(Color online) The parameter *a* in Eq. (4) as a function of temperature for devices A and B, as indicated. The solid curves are the least-squares fits to Eq. (5). The dashed curves are the theoretical predictions of the same equation, but plotted by directly substituting the and values extracted from the fits to Eq. (1).

(Color online) Variation of saturation current with temperature for (a) devices A and (b) device B and variation of critical voltage with temperature for (c) device A and (d) device B. Notice that these two parameters are temperature independent within our experimental uncertainties.

(Color online) Variation of saturation current with temperature for (a) devices A and (b) device B and variation of critical voltage with temperature for (c) device A and (d) device B. Notice that these two parameters are temperature independent within our experimental uncertainties.

## Tables

Values of relevant parameters for two NW devices. Device A (B) has a NW diameter of 70 (100) nm. The junction (nanocontact) area was estimated from the SEM image and given by the product of the diameter of the NW and the average extent of the two Au contacting electrodes lying beneath the NW. The specific contact resistivity is defined by = and ( K). The intrinsic NW resistance for device A (B) is 2 ( 1) and weakly dependent on temperature, as determined by the four-probe method in Ref. 4. The total Au electrode resistances are 10 .

Values of relevant parameters for two NW devices. Device A (B) has a NW diameter of 70 (100) nm. The junction (nanocontact) area was estimated from the SEM image and given by the product of the diameter of the NW and the average extent of the two Au contacting electrodes lying beneath the NW. The specific contact resistivity is defined by = and ( K). The intrinsic NW resistance for device A (B) is 2 ( 1) and weakly dependent on temperature, as determined by the four-probe method in Ref. 4. The total Au electrode resistances are 10 .

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