[paper] Three-Gated Reconfigurable FETs

Giulio Galderisi, Christoph Beyer, Thomas Mikolajick, and Jens Trommer 

Insights into the Temperature Dependent Switching Behaviour of Three-Gated Reconfigurable Field Effect Transistors 

physica status solidi (a) DOI: 10.1002/pssa.202300019

NaMLab gGmbH Dresden (D) 

TU Dresden, Chair of Nanoelectronics, Dresden (D) 

Abstract: Three-Gated Reconfigurable Field Effect Transistors are innovative nanoelectronic devices that are rapidly and increasingly attracting substantial interest in several fields of application thanks to their inherent n-type/p-type reconfiguration capabilities. For this reason, it is of significant importance to acquire a deeper knowledge about the temperature ranges in which such devices can be operated and, at the same time, gather a better understanding of the physical mechanisms that are involved in their operation. To achieve this aim, in-depth observations about the functioning of such devices in an ultra-wide temperature range, spanning from 80 K to 475 K, were performed and are presented for their ambipolar and lowVT operation modes. In view of the data exhibited in this work, it is possible to assess the performances of Three-Gated Reconfigurable Field Effect Transistors within a considerable temperature span and finally provide significant insights on the temperature dependent physical mechanisms regulating their functionality.

FIG: a) Typical Three-Gated RFET transfer characteristic, showing both p-/n-type curves for lowVT and highVT operations together with the ambipolar mode. b) Cross-sectional depiction of a Three-Gated RFET. c) False-colored SEM image of fabricated RFET device, based on 60 nm wide nanochannel. d) Schematic band diagrams of the most relevant operation modes of a Three-Gated RFET: off-states for both lowVT and highVT modes are shown, together with the on-state, which is the same for both operations. e) Table summarizing the possible RFET operations: the highlighted ones will be analyzed in this paper. f) Three-Gated RFET fabrication process flow. g) Ambipolar transfer curves for p/n-type branches, obtained on a different set of devices: the shaded area around the solid line (mean) shows the standard deviation calculated on 50 measured devices. h,i) P-type and n-type transfer curves of the lowVT mode for different values of the drain voltage. l,m) P-type and n-type transfer curves of the lowVT mode for different values of the program voltage. In m) it is possible to observe a shift in the VT when the device is programmed at 1 V: this non-ideality is probably due to traps generated in the gate oxide during measurement. 

Acknowledgements: This work was supported in part by the State budget by the delegates of the Saxon State Parliament and in part by the German Research Foundation (DFG) within the projects number 326384402 and SPP2253 under project number 439891087.