An Area Equivalent WKB Approach to Calculate the B2B Tunneling Probability for a Numerical Robust Implementation in TFET Compact Models

This paper presents a novel approach to calculate the band-to-band (B2B) tunneling probability in tunnel-field effect transistors (TFETs) for the usage in compact models. The tunneling barrier is defined by a compact solution of the electrostatics and is approximated by an area equivalent triangular profile. For this profile the Wentzel-Kramers-Brillouin approximation (WKB) is applied. Referring to the area instead of the electric field at single points is shown to be more robust regarding numerical stability. By comparing the results of the approach with numerical TCAD Sentaurus simulation data of a double-gate (DG) TFET for various bias conditions and geometric positions within the device, the numerical stability as well as the limitations are demonstrated. Furthermore, the comparison to a quasi-2D WKB approach, the derived model shows a better fit to TCAD data at a reduced complexity.