Physical reservoir application of random network of gold nanoparticles fabricated by multi-step immersion in gold colloidal solution

We fabricated a random network of gold nanoparticles (RN-GNPs) over 12 NiCr/Au electrodes by using a multi-step immersion method, where a sample was immersed in a gold colloid solution three times. Nonlinear current-voltage characteristics due to the Coulomb blockade were observed at 77 K. For demonstration of physical reservoir applications, input-output characteristics of the RN-GNPs were also measured in a one-input, nine-output terminal configuration. Distorted output voltage waveforms were obtained for a sinusoidal voltage input of 100 Hz. The higher-order harmonic components were confirmed in the frequency spectra of the outputs. The waveform reconstruction task and short-term storage capacity estimation were performed by an echo state network model with ridge regression and linear regression, respectively.