Tunable rectification and slope reversals in the I-V characteristics of ballistic nanojunctions

We investigate nonlinear effects at low temperature in the I-V characteristics of four-terminal nanojunctions fabricated from InGaAs/ InAlAs heterostructures. The rectified voltage can be tuned by applying biases on side gates, as well as by changing cooldown conditions, I i.e., by controlling the conductances of the junctions' channels. In addition, we observe reversals in the slope of the I-V curves as the probe current grows. These reversals coincide with abrupt changes in the channels' conductances. We discuss possible interpretations of these observations, and provide a comparison with previous experimental results. (c) 2006 Elsevier B.V. All rights reserved.