Analytical model of nanowire geometric diodes

Nanowire geometric diodes have unique properties which allow them to function as long wavelength energy harvesters and ultra-high speed signal processors. Geometric diodes operate through symmetry breaking on a scale comparable to the mean-free-path length of charge carriers. Through dopant encoded vapor-liquid-solid growth, followed by wet chemical etching, nanowires can be experimentally fabricated into “sawtooth nanowires”. Sawtooth nanowires exhibit diodie-like behavior (current at an applied voltage is directionally asymmetric) due to the geometric diode effect. Sawtooth geometries are defined by three parameters, length, inner diameter, and outer diameter, and all impact the overall resistance, I-V characteristics, and frequency dependence.

We aim to predict the device’s asymmetry dependence on these parameters through a model which calculates the ratio of possible paths ballistic electrons can travel through the wire. The trends predicted by the model are strongly backed by experimental data. We show that the strongest factor controlling asymmetry is the sawtooth angle, a combined metric of neck diameter and sawtooth length. We can use this model to optimize the design of geometric diodes in order to tailor their properties for specific applications.