Comprehensive Study of Inversion and Junctionless Ge Nanowire Ferroelectric HfZrO Gate-All-Around FETs Featuring Steep Subthreshold Slope with Transient Negative Capacitance

This study reports the ferroelectric (FE) layer of Hf 0.5 Zr 0.5 O 2 (HZO) film on a Ge gate-all-around field-effect-transistor (GAAFET) with inversion mode (IM) and junctionless (JL) mode, and is the first that discuss the association of the JL field-effect transistor conduction mechanism in the subthreshold region with the transient negative capacitance (TNC) effect of the FE layer are discussed. The IM Ge FE-GAAFET exhibited a minimum subthreshold slope (SS min ) of 55 mV dec −1 and a high I ON /I OFF ratio of >10 6 . The sub-60 mV dec −1 SS result demonstrates surface potential amplification, which is attributed to the TNC effect. Furthermore, the Ge JL FE-GAAFETs exhibited an SS min of 58 mV dec −1 , a high I ON /I OFF ratio (>10 5 ), and reverse drain-induced barrier lowering when compared with baseline HfO 2 devices. These IM and JL Ge FE-GAAFETs are highly suitable for low-power integrated circuit applications.