  The current-voltage characteristics of thin wires are often observed to be
nonlinear, and this behavior has been ascribed to Schottky barriers at the
contacts. We present electronic transport measurements on GaN nanorods and
demonstrate that the nonlinear behavior originates instead from
space-charge-limited current. A theory of space-charge-limited current in thin
wires corroborates the experiments, and shows that poor screening in high
aspect ratio materials leads to a dramatic enhancement of space-charge limited
current, resulting in new scaling in terms of the aspect ratio.
