Fringing field induced current coupling in concentric metal–insulator–semiconductor (MIS) tunnel diodes with ultra-thin oxide

Coupling phenomenon between two Al/SiO2/Si(p) metal–insulator–semiconductor (MIS) tunneling diodes (TD) with various thin oxide thicknesses was studied in detail. When the bias voltage at one MIS TD is positive enough, the saturation currents of the two neighboring MIS TDs with concentric gate structures would be approximately the same due to saturation current coupling effect though the areas of these two devices are different. With thinner oxide, the saturation current coupling effect occurs earlier. This result indicates an enhancement of coupling sensitivity between two neighboring MIS TDs with thinner oxide. A physical mechanism of lateral minority carrier flow attracted by the fringing field was given to explain this phenomenon. Moreover, this oxide thickness dependent phenomenon of coupling effect was confirmed by capacitance–voltage (C–V) characteristics, and the fringing field extension and strengthening were clarified by 2D TCAD simulation.