Off-State Leakage Induced by Band-to-Band Tunneling and Floating-Body Bipolar Effect in InGaAs Quantum-Well MOSFETs

The physics of off-state drain leakage (Ioff) in scaled self-aligned InGaAs quantum-well (QW) MOSFETs is investigated through experiments and simulations. Excess Ioffis observed in InGaAs QW-MOSFETs with very short contact-to-channel spacing. This current bears the marks of band-to-band tunneling (BTBT) that takes place at the drain edge of the channel. However, a pure BTBT current does not explain the observed magnitude of Ioffnor its gate length dependence. For this, we invoke floating-body bipolar amplification of the BTBT current in the QW channel. Device simulations that include BTBT and drift diffusion are consistent with the magnitude of the experimental Ioffand its gate length scaling behavior. The understanding derived here suggests a number of paths to mitigate BTBT-induced off-state current in scaled InGaAs QW-MOSFETs.