Effect of Hf x Zr1−x O2/Ge metal–ferroelectrics–insulator–semiconductor interfaces on polarization reversal behavior

Abstract

Abstract To evaluate the polarization characteristics of ferroelectric-gate field-effect transistors, metal–ferroelectrics–insulator–semiconductor (MFIS) structures are often used. This study examines the influence of interface characteristics on polarization characterization in MFIS on low-impurity-concentration substrates by experimentally evaluating the ferroelectric properties of Hf x Zr1−x O2 (HZO)/Ge MFIS capacitors with different interface properties. Usually, polarization reversal behavior is not observed for MFIS capacitors on low-impurity-concentration substrates. However, it is found that, when the interface properties are poor and the interface state density is high, polarization reversal behavior can be observed even on the low-impurity concentration substrates. In lightly-doped MFIS capacitors with many interface states, the response of the interface states at low measurement frequencies suppresses the depletion layer change and voltage drop in the Ge substrate, resulting in the high electric field across the HZO films and observation of polarization reversal behavior.