The combined effects of band-to-band tunneling and impact ionization in the off regime of an LDD MOSFET

Fully self-consistent two-dimensional simulation of band-to-band tunneling (BTBT) in a lightly doped drain (LDD) MOSFET is reported. The simulation results are compared to experimental data and explain the observed current leakage effects. At low drain bias the leakage currents in the off regime can be explained by BTBT alone. At high drain bias and at deep subthreshold gate bias the leakage current is increasingly due to avalanche generation by carriers created initially in BTBT and accelerated subsequently in the high electric fields.>