  In this work, we theoretically and experimentally investigate the working
principle and non-volatile memory (NVM) functionality of 2D
$\alpha$-In$_2$Se$_3$ based ferroelectric-semiconductor-metal-junction (FeSMJ).
First, we analyze the semiconducting and ferroelectric properties of
$\alpha$-In$_2$Se$_3$ van-der-Waals (vdW) stack via experimental
characterization and first-principle simulations. Then, we develop a FeSMJ
device simulation framework by self-consistently solving
Landau-Ginzburg-Devonshire (LGD) equation, Poisson's equation, and
charge-transport equations. Based on the extracted FeS parameters, our
simulation results show good agreement with the experimental characteristics of
our fabricated $\alpha$-In$_2$Se$_3$ based FeSMJ. Our analysis suggests that
the vdW gap between the metal and FeS plays a key role to provide FeS
polarization-dependent modulation of Schottky barrier heights. Further, 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 5.47x increase in sense margin, 18.18x reduction in area and lower
read-write power with respect to Fe insulator tunnel junction (FTJ).
