New type steep-S device using the bipolar action

We have proposed an alternative approach for developing a steep subthreshold swing FET that is less than the theoretical diffusion-based limit of 60 mV/decade at room temperature. Instead of using a simple IGFET, we formed a complex device in a “single device” and worked it as a sub-circuit, which resulted in a steep subthreshold swing. We formed a tunnel junction in a drain diffusion layer of the MOSFET so that we could stuff a tunnel-injection bipolar, a resistor, and a MOSFET inside a single “scaled MOSFET”. We used device simulation to clarify the concept of “device complex”. Results showed a steep subthreshold swing even if the supply voltage was low (~0.2 V).