Current–voltage characteristics of GaAs nanowhiskers

The current–voltage characteristics of GaAs whiskers with an average diameter of 100 nm and a population of 100–1000 were measured using a device structure with two terminal electrodes. An ohmic contact to the tip of whiskers which were buried in spin-on glass between a metal electrode and n-type GaAs(1 1 1)As substrate was realized by heat treatment at 430 °C. The measured results show that the current–voltage curve for the whiskers is better approximated by the polynomial of the voltage to the power of 1.5 than by the exponential of the voltage. The dependence of the current on the voltage suggests that a space-charge layer was formed in the nanowhiskers. Step-like current fluctuations were also observed at 77 K, and this behavior was reproducible and unchanging even under a magnetic field. This suggests that the charge on the surface of the whiskers had a significant effect on carrier transport along the whiskers.