Electrical Activity and Extremes of Individual Suspended ZnO Nanowires for 3D Nanoelectronic Applications.

ABSTRACT

We explored the electrical activity and extremes inside individual suspended zinc oxide (ZnO) nanowires (NWs) (diameter 50-550 nm, length 5-50 µm) subjected to high forward bias-induced Joule heating using two-terminal current-voltage measurements. NWs were isolated using a reproducible nanometrology technique, employing a nanomanipulator inside a scanning electron microscope. Schottky behavior is observed between installed tips and ZnO NW. The suspended ZnO NWs exhibited an average electrical resistivity ρ (approximately 2.3 × 10-2 Ω cm) and a high electron density n (exceeding 1.89 × 1018 cm-3), comparable to that of InP NWs, GaN NWs, and InAs NWs (1018∼1019 cm-3), suggesting the potential to drive advancements in high-performance NW devices. A maximum breakdown current density (JBD) of ∼0.14 MA/cm2 and a maximum breakdown power density (PBD) of 6.93 mW/µm3 were obtained, both of which are higher than substrate-bound ZnO NWs and consistent with previously reported results obtained from probed ZnO NWs grown vertically on the substrate. Moreover, we discovered that NWs experienced thermal breakdown due to Joule heating and exploited this breakdown mechanism to further investigate the temperature distribution along the ZnO NWs, as well as its dependence on the electrical properties and thermal conductance of contact electrodes. Thermal conductance was determined to be ∼0.4 nW K-1 and ∼1.66 pW K-1 at the tungsten(W)-ZnO NW and platinum(Pt)-ZnO NW contacts, respectively. In addition, we measured the elastic modulus (130-171 GPa), which closely approximated bulk values. We also estimated the nanoindentation hardness to be between 5 and 10 GPa. This work provides valuable insights into the electrical activity and extreme mechanisms, thus providing a better understanding of the potentials and limitations associated with utilizing suspended NWs in 3D nanodevices.