Study of TFET non-ideality effects for determination of geometry and defect density requirements for sub-60mV/dec Ge TFET

Tunneling Field Effect Transistor (TFET) has attracted interest due to its steep-SS prospects [1]. Although a number of sub-60mV/dec TFETs were demonstrated [2], many failed to realize this feat due to non-optimized geometry, material choice [3], and material defects [4, 5]. In this paper, we clearly distinguish the requirement for i) geometry, ii) semiconductor BTBT characteristics, iii) semiconductor defects and iv) oxide interface defects. Using Ge as a case study, multi-temperature characterization of experimental PIN diodes is used to separate bulk properties from the interface effects, calibrating the models for BTBT, trap-assisted-tunneling (TAT) and SRH. The measured BTBT characteristic of a material is as important as the effect of defects; even a zero-defect TFET using the calibrated Ge material requires thin body and thin oxide. Bulk SRH and TAT is found to be a less critical issue for thin body TFETs, whereas interface defect density ~10¹²cm^-2 is low enough to only degrade TFET SS <;10mV/dec. The method of current component segmentation using multi-temperature short-intrinsic PIN diodes is essential for evaluation of materials for TFETs.