Analytical electron billiards model of geometric diodes

Unlike traditional diodes that require a potential barrier to generate electrical asymmetry, geometric diodes operate simply by breaking the structural symmetry on a scale comparable to the mean-free-path length of charge carriers. This gives geometric diodes unique properties that allow them to function as long wavelength energy harvesters and ultra-high speed signal processors. These devices exhibit nonlinear charge transport that is largely dictated by geometric parameters and position-dependent mean-free-path. We aim to predict the device’s dependence on these parameters through analytically calculating the proportion of possible paths ballistic charge carriers can travel through the device. Trajectories of up to an arbitrary number of internal reflections are integrated over all space inside the device. To account for the effect of applied electric field on the electron momentum distribution, a spatial distribution weighted in one direction is used and the impact on diode asymmetry is evaluated. The model is able to simulate nonlinear charge transport in both 2D and 3D nanowire geometric diodes. The model has excellent agreement with experiment, matching trends of IV curve asymmetry versus geometric parameters in silicon nanowire geometric diodes.