The Interplay of Nanocontact and Electrical Properties of ZnO and InP Nanowires and Polyaniline Nanofibers
- PDF / 610,028 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 31 Downloads / 193 Views
1198-E08-06
The Interplay of Nanocontact and Electrical Properties of ZnO and InP Nanowires and Polyaniline Nanofibers Yen-Fu Lin and Wen-Bin Jian Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan ROC ABSTRACT The interface problems in nanomaterial based electronics play important roles. We have learned that the nanocontact, due to its reduced contact area, could give a high electrical contact resistance and a nonlinear current-voltage behavior though the specific contact resistance is in the same order of magnitude as that of macroscopic contacts. Through the current-voltage and temperature behaviors, the nanocontact properties could be categorized into Ohmic and Schottky types. The electrical properties of the nanowire based two-probe devices could be rationalized as two Ohmic contacts, one Ohmic and one Schottky contacts, and two back-to-back Schottky contacts. Moreover, the nanocontact could be treated as a one-dimensional disordered electron system for further studies. After the intrinsic nanowire and contact resistances are separated from each other, the electron transport and the carrier concentration of native doping in ZnO and InP nanowires can be determined. The nanowires are determined to have low carrier concentrations, implying a high sensitivity to light and gas. The contact and nanowire dominated two-probe devices are exposed to light and gas to identify the contact effects. In addition to the inorganic nanowires, the organic nanomaterials, the HCl-doped polyaniline nanofibers, can be analyzed by using the same approach. The dielectrophoresis technique is implemented to position nanofibers into an electron-beam lithographically patterned nanogap. To shine the electron-beam on contact areas, the organic/inorganic nanocontact resistance is reduced so as to probe the intrinsic electrical property of a single polyaniline nanofiber. INTRODUCTION It has been pointed out, for more than ten years ago, that the nanocontact resistance should be taken into account when probing electrical transport in nanomaterials [1]. Bachtold et al. [2] applied four-probe electric measurements to carbon nanotubes and found that the contact resistances decrease by orders of magnitudes after the contact areas are exposed to electron beam. Yu et al. [3] employed four-probe measurements to separate the voltage dependent resistance in Si nanowires from that in the nanocontact. Appenzeller et al. [4] explored the role of contacts that affect the Schottky barriers between a three-dimensional metal and a low-dimensional semiconductor of carbon nanotube. Hwang et al. [5] discovered that the contact resistance is reduced as the Ti layer thickness, in the Ti/Au electrodes contacting on GaN nanowires, is increased. Mohney et al. [6] and Gu et al. [7] proposed and experimented new approaches to determine the nanowire resistance and to eliminate the contact contribution. Nam et al. [8] started to discuss disorder effects in Pt contacts on GaN nanowires that results in variable range hop
Data Loading...
