Alpha-In2se3 Based Ferroelectric-Semiconductor Metal Junction For Non-Volatile Memories

In this work, we theoretically and experimentally investigate the working principle and nonvolatile memory (NVM) functionality of a 2D alpha-In2Se3-based ferroelectric-semiconductor-metal-junction (FeSMJ). First, we analyze the semiconducting and ferroelectric properties of the alpha-In2Se3 van der Waals (vdW) stack via experimental characterization and first-principles simulations. Then, we develop a FeSMJ device simulation framework by self-consistently solving the Landau-Ginzburg-Devonshire equation, Poisson's equation, and charge-transport equations. Based on the extracted Fe-semiconductor (FeS) parameters, our simulation results show good agreement with the experimental characteristics of our fabricated alpha-In2Se3-based FeSMJ. Our analysis suggests that the FeS polarization-dependent modulation of Schottky barrier heights of FeSMJ plays a key role in providing the NVM functionality. Besides, the appearance of mobile carriers in FeS due to its semiconducting properties leads to a non-uniform electric field. This further induces partial polarization switching in the FeS layers, resulting in asymmetry in the FeSMJ characteristics for positive and negative voltages. Moreover, we show that the thickness scaling of FeS leads to a reduction in read/write voltage and an increase in distinguishability. Array-level analysis of FeSMJ NVM suggests a lower read-time and read-write energy with respect to the HfO2-based ferroelectric insulator tunnel junction.