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 (J
BD) of ∼0.14 MA/cm2 and a maximum breakdown
power density (P
BD) 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.