A Theoretical Analysis of Ferroelectric Switching Physics in Metal/Ferroelectric/IGZO Stack Toward Interlayer-Free FeFETs

Compared to Si, IGZO is a competitive choice for FeFET channel material, because of the interlayer-free structure, which can lead to a higher endurance. However, the ferroelectric switching mechanism of erasure remains unclear due to the lack of holes in IGZO. In this work, we present a quasi-static charge sheet model of Metal/Ferroelectric/IGZO stack, considering the charges supplied by IGZO Density of States and interface states. The modeling results suggest that shallow donors, by emitting electrons into the conduction band and thereby partially ionized, can become positively charged and thus support the erase operation. Cryogenic Negative Bias Illumination Stress measurement indicates the presence of shallow donors.