5 nm Ultrathin Crystalline Ferroelectric P(VDF‐TrFE)‐Brush Tuned for Hysteresis‐Free Sub 60 mV dec−1 Negative‐Capacitance Transistors

• Published in: Advanced materials (Weinheim) Vol. 35; no. 22; pp. e2300478 - n/a
• Main Authors: Cho, Hyunmin, Jin, Hye‐Jin, Lee, Sol, Jeon, Seungbae, Cho, Yongjae, Park, Sam, Jang, Myeongjin, Widiapradja, Livia Janice, Ryu, Du Yeol, Park, Ji Hoon, Kim, Kwanpyo, Im, Seongil
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.06.2023
• Subjects: Brushes; Capacitance; Difluorides; Energy dissipation; Ferroelectric materials; Ferroelectricity; Field effect transistors; Hysteresis; hysteresis‐free operation; Integrated circuits; Materials science; MoS 2; negative capacitance; P(VDF‐TrFE)‐brushes; subthreshold swing; Thickness; Transistors; Vinylidene; MoS 2; subthreshold swing; field-effect transistors; hysteresis-free operation; negative capacitance; P(VDF-TrFE)-brushes
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202300478

Negative‐capacitance field‐effect transistors (NC‐FETs) have gathered enormous interest as a way to reduce subthreshold swing (SS) and overcome the issue of power dissipation in modern integrated circuits. For stable NC behavior at low operating voltages, the development of ultrathin ferroelectrics (FE), which are compatible with the industrial process, is of great interest. Here, a new scalable ultrathin ferroelectric polymer layer is developed based on trichloromethyl (CCl3)‐terminated poly(vinylidene difluoride‐co‐trifloroethylene) (P(VDF‐TrFE)) to achieve the state‐of‐the‐art performance of NC‐FETs. The crystalline phase of 5–10 nm ultrathin P(VDF‐TrFE) is prepared on AlOX by a newly developed brush method, which enables an FE/dielectric (DE) bilayer. FE/DE thickness ratios are then systematically tuned at ease to achieve ideal capacitance matching. NC‐FETs with optimized FE/DE thickness at a thickness limit demonstrate hysteresis‐free operation with an SS of 28 mV dec−1 at ≈1.5 V, which competes with the best reports. This P(VDF‐TrFE)‐brush layer can be broadly adapted to NC‐FETs, opening an exciting avenue for low‐power devices. An ultrathin crystalline ferroelectric polymer based on trichloromethyl (CCl3)‐terminated poly(vinylidene difluoride‐co‐trifloroethylene) (P(VDF‐TrFE)) is developed on AlOX to realize negative‐capacitance metal–oxide–semiconductor field‐effect transistors (MOSFETs) with a MoS2 channel. Systematic adjustment of the thickness ratio between the polymer and dielectric AlOX achieves a hysteresis‐free FET with a minimum subthreshold swing of 28 mV dec−1, operating at less than 2 V.