Tunneling FETs on SOI: Suppression of ambipolar leakage, low-frequency noise behavior, and modeling

We report on thin-body tunneling field-effect transistors (TFETs) built on SOI substrates with both SiO2 and HfO2 gate dielectrics. The source-drain leakage current is suppressed by the introduction of an intrinsic region adjacent to the drain, reducing the electric field at the tunnel junction in the off state. We also investigate the temperature dependence of the TFET characteristics and demonstrate that the temperature-induced change in the Si bandgap is the main mechanism that determines the tunneling barrier and hence the drain current ID. We present a model of the TFET as a combination of a gated diode and a MOSFET, which can be solved analytically and can predict the experimentally measured ID over a wide range of drain and gate bias. Finally we report on the low frequency noise (LFN) behavior of TFETs, which unlike conventional MOSFETs exhibits 1/f2 frequency dependence even for large gate areas. This dependence indicates less trapping due to the much smaller effective gate length over the tunneling junction.