Samsung Advanced Institute of Technology

Negative differential capacitance (NDC) of ferroelectrics can be utilized to overcome the limitations of capacitive coupling using conventional high-k dielectrics in electronic devices. By adding dielectric onto the ferroelectric material, the NDC can be stabilized, by which the voltage to the dielectric can be amplified above the applied one in the whole system. Realizing and controlling NDC in scaled Si-based structures is crucial for the application to advanced low-power logic devices, which still remains elusive. Here, we integrated ferroelectric Hf_0.5Zr_0.5O₂ (HZO) films with a thickness down to 1 nm ？verified through different crystallographic and electric characterizations？ on the metal oxide semiconductor capacitor (MOSCAP) structure, which significantly outperformed the physically thinner control devices devoid of the HZO films. The 'S’-shaped polarization-electric field (P-E) relation in the HZO verified the presence of the NDC effect, leading to 9.8 ％ enhanced charge accumulation than the theoretical limit with infinitely high-k dielectrics. Also, both the enhanced on-current and reduced off-current observed by replacing the high-k HfO₂ with the ferroelectric HZO in the field effect transistor (FET) was identified as being from the occurrence of the NDC through demonstrating the negative drain-induced-barrier-lowering with 'S’-shaped P-E relation. With the boosted performance in both MOSCAP and FET by the NDC, the endurance of >10¹⁵ and tunability, achieved through a proper control of the interfacial charge by introducing dopants, observed in our study could enable the application of ultra-scaled ferroelectric materials in designing future low-power devices.