Effect of insulator thickness on the electronic transport through CNT-HfO₂-Au junction for optical rectenna applications

Using density functional theory in combination with nonequilibrium Green's functional formalism we study the effect of the insulating layer on the current rectification properties of CNT-HfO₂-Au junction, which has a great potential for optical rectenna applications. We found that the asymmetricity (i.e., the rectification ratio) and nonlinearity averaged over the bias voltages increase linearly with the layer thickness d, whereas the differential resistance increases exponentially with increasing d. The obtained results are explained using the analysis of density of states, transmission spectra, electrostatic potential profile and molecular projected self-consistent Hamiltonian states. These findings can be useful for creating CNT-based diodes with desired performance metrics for different optoelectronic applications.