Switching Behavior in a Vertical Tunneling Transistor by Tunneling Mechanism Transition and Floating Electrode Structure

Direct application of the tunneling mechanism into the conventional field-effect transistor structure only results in inefficient switching behavior and high leakage current. Here, we report a vertical metal–insulator–metal (MIM) tunneling transistor employing a floating electrode to achieve an efficient switching behavior and substantially low leakage current simultaneously. This switching method utilizes a tunneling mechanism transition between direct and Fowler–Nordheim tunneling by placing the floating electrode into a vertical tunneling channel. Engineering the electrical potential of the floating electrode with coplanar dual gates enables the efficient control of the tunneling mechanism transition. This particular arrangement of the gate and source/drain (no overlap) allows an extremely low gate leakage current (∼10–13 A). This value is significant in the tunneling transistor and promising for future electrical devices with low-power consumption. Furthermore, tunneling, whose operating principle is fundamentally different from the p–n junction and Schottky barrier in the Si transistor, has been proposed as a solution to tackle the issues such as high-frequency driving, power consumption, and so on. This structure is a strong candidate for ultrahigh-frequency driving because of its extremely low structural capacitance (∼1.5 zF). An additional electrical status can be shown to generate ternary or more statuses in a single transistor. Its electrical performance is expected to not only harmonize with THz communication systems, control process units, and high-speed electrical systems but also contributes a degree of integration. Moreover, the simple and low-temperature fabrication process of the vertical MIM tunneling transistor is advantageous for low-cost electrical devices and flexible electronic applications.