Simulating the Barrier Heights Impact on the Performance of Dissimilar Electrodes Metal-Insulator-Metal Diode

Metal-insulator-metal (MIM) tunnel diodes are desirable for applications including ultra-high frequency rectenna detectors, solar cells, and mixers due to their femtosecond-fast transmission. These applications place strict demands on the current-voltage I(V) properties of diodes. In this paper, a single insulator tunnel diode is simulated using SILVACO ATLAS software to correlate the importance of insulator interfacial stability to MIM rectification performance, which helped to analyse and develop MIM diodes with the desired properties. By keeping the Al2O3 insulator layer, different metals were used as electrodes of the MIM diode to achieve the desired asymmetry. Two schemes of electrode asymmetry were proposed, the first scheme is based on using a metal that produces a constant barrier height at one side of the insulator layer and different barrier heights at the other by using different metals. The second structure implicates using different metals at the sides of the insulator to achieve different barrier heights but with constant barrier differences between the metals. A voltage range of.0.4 V was used to study electrical characteristics. It is found that the MIM structure with fixed barrier height at cathode side produces a good asymmetry with poor nonlinearity, while the results of fixed barrier height at anode side reveals that the figure of merit (FOM) strongly depends on the work function difference of the metals of the MIM structure. For the constant barrier differences, it is found that the smaller the barrier height the larger the current response produced and the lower the turn on voltage. The impact of insulator thickness on the diode FOM shows that the lowest thickness produces the highest asymmetry and nonlinearity.