3. Compact Models of TFETs

Rapid developments in the TFETs’ process and rising interests in evaluating their potential in low-power circuits/systems require a TFET compact model for SPICE simulations. In this chapter, we discuss the essential device physics of TFETs, propose necessary simplifications of their complex operations, and develop a core model for homojunction TFETs. At first, we analyze the roles of TFET channel charge in affecting their subthreshold swing and superlinear output. Bearing this in mind, we divide the TFET structure into three distinctive regions for the purposes of considering the channel charge and at the same time getting a closed-form solution of the device electrostatics. After that, we find a simplification to the integration formulation of the interband tunneling physics to derive the current model. With a straightforward derivation, we obtain the terminal charge model and therefore finish the core model development. Around this core, we are adding advanced effect modules and specifically introduce the gate leakage module and short-channel effect module here. Finally, we analyze the basic operations of heterojunction TFETs and possible challenges in their model developments.