An Impact Ionization MOSFET With Reduced Breakdown Voltage Based on Back-Gate Misalignment

In this paper, we propose a misaligned double-gate p-i-n impact ionization MOS (MIMOS) with a deliberate misalignment between the top and bottom gates. The presence of a misaligned bottom gate leads to band-to-band-tunneling of electrons at the source-intrinsic region interface and increases the number of carriers for impact ionization. The electric field redistribution provides a longer transport path for the carriers. Therefore, carriers gain higher kinetic energy, and the impact ionization rate is enhanced in the MIMOS. This results in a significantly lower avalanche breakdown voltage compared to conventional single-gate IMOS structure. Using calibrated 2-D simulations, we demonstrate that MIMOS exhibits a steep subthreshold slope (similar to 6 mV/dec) at a significantly low-supply voltage of (V-DS = 0.59 V), which is similar to 48% lower than that of the corresponding single-gate IMOS (V-DS = 1.15 V).