Ferroelectric field-effect transistors (FeFETs) with semiconductors as the channel material and ferroelectrics as the gate insulator are attractive and/or promising devices for application in nonvolatile memory. In FeFETs, the conductivity states of the semiconductor are utilized to explore the polarization directions of the ferroelectric material. Herein, we report FeFETs based on a few layers of MoS2 on a 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single crystal with switchable multilevel states. It was found that the On-Off ratios can reach as high as 106. We prove that the interaction effect of ferroelectric polarization and interface charge traps has a great influence on the transport behaviors and nonvolatile memory characteristics of MoS2/PMN-PT FeFETs. In order to further study the underlying physical mechanism, we have researched the time-dependent electrical properties in the temperature range from 300 to 500 K. The separation of effects from ferroelectric polarization and interfacial traps on electrical behaviors of FeFETs provides us with an opportunity to better understand the operation mechanism, which suggests a fantastic way for multilevel, low-power consumption, and high-density nonvolatile memory devices.
Keywords: MoS2; PMN−PT single crystal; ferroelectric field-effect transistor; hysteresis; multilevel memory.