Negative capacitance gate stack and Landau FET-based voltage amplifiers and circuits: Impact of ferroelectric thickness and domain variations

Abstract

This article analyzes the impact of ferroelectric hafnium zirconium oxide (HZO) thickness (tFE) and domain number (N) variations on the negative capacitance (NC) effect in metal/HZO/metal gate stack and its implications on Landau FET-based device-circuit co-design through simulations. As tFE decreases, the NC effect weakens, resulting in less S-shaped hysteresis loops for charge and polarization versus voltage characteristics. The study highlights the trade-off between energy dissipation and NC effect voltage window in ferroelectric devices and the importance of balancing both. We developed Landau FET-based voltage amplifiers (VA), including passive VA (PVA) and active VA (AVA), and compared to existing counterparts such as P(VDF-TrFE)-PVA and PZT-AVA, across low and high frequencies. The proposed PVA shows a 22.60% and 54.31% increase in amplification (ANC) at low and high frequencies, respectively, compared to P(VDF-TrFE)-PVA. The AVA exhibits a 17.86% increase in ANC at low frequencies compared to PZT-AVA but no ANC at higher frequencies due to symmetry-breaking. The Landau FET-based inverter shows a sharp state transition than the CMOS inverter, but this sharpness depends on tFE, N, and the degree of NC effect. The Landau FET-based fan-out-4 inverter with 7.7 nm tFE and N = 16 is 25.49% faster than the Si MOSFET inverter. Moreover, the impact of tFE and N on the performance of the proposed 5-stage ring oscillator (RO) is investigated concerning state-of-the-art CMOS RO counterparts. The 5-stage RO using Landau FET-based inverters showed (1.26–18.9) times higher oscillation frequency (fOSC) and (17.93–5.71) times reduced power dissipation compared to the existing CMOS ROs. Finally, we examined how process variations impact the fOSC in the proposed 5-stage Landau FET-based RO. The findings indicate a standard deviation of 0.39 GHz in the distribution of fOSC. These findings highlight the interplay between tFE scaling, N variations, and transient NC effect, advancing Landau FET-based devices for future NC electronics.