Electric Field Cycling-mediated Variations in Defect Distributions Associated with Split-up Behavior of a Ferroelectric Si-doped HfO2 Thin Film

Abstract

We report variations in the characteristic ferroelectric switching time and interface free carrier concentration associated with the wake-up and split-up behaviors of a 4.2 mol % Si-doped HfO2 thin film. Prior to the development of split-up behavior, the thin films exhibited the wake-up behavior; the remnant polarization increased on repeated external bias cycling. After the wake-up behavior, Si-doped HfO2 films exhibited degradation of the remnant polarization values and splitting of the ferroelectric switching current peaks when the external bias was swept; this is referred to as split-up behavior. An investigation of the ferroelectric switching dynamics revealed retardation, followed by recovery, of the characteristic switching time for ferroelectric nucleation, coincident with the wake-up and split-up behaviors, respectively. We analyzed the interface free carrier concentration by deriving capacitance-voltage characteristics and revealed that split-up behavior was associated with increased numbers of defects as electric field cycling continued.

이 논문에서는 강유전성 스위칭 시간과 계면의 자유 전하 밀도와 관련하여 wake-up 현상과 split-up 현상에 대해 4.2% mol 실리콘 도핑 된 산화물 하프늄을 이용하여 연구하였다. Split-up에 앞서, 박막은 전기장 전계에 따라 잔류 분극이 증가하는 wake-up 현상을 보였다. Wake-up 현상 이후, 외부 전기장에 의해 잔류 분극 값이 감소하였고 강유전성 스위칭에 의한 전류 분포가 나누어지는 현상, 즉 split-up 현상을 보였다. Nucleation limited switching 모델을 기반으로 한 강유전성 스위칭 동역학을 통해 분석하였을때, 강유전성 핵생성을 위한 스위칭 시간은 wake-up과 split-up현상에 따라 각각 느려지고, 빨라졌다. 이와 함께 전압-전기용량 특성의 결과를 분석하였을 때, 박막내 결함의 증가가 split-up 현상에 영향을 주는 것으로 생각된다.