High tunneling electroresistance in ferroelectric tunnel junctions based on two-dimensional α-InSe/MoTe van der Waals heterostructures.

Ferroelectric polarization-controlled band alignment can be realized in van der Waals heterostructures (vdWHs), which can be used to create new types of ferroelectric tunnel junctions (FTJs). In this work, we design six probable configurations of two-dimensional vdWHs based on a two-dimensional α-InSe ferroelectric material which has two opposite polarization states P↑ and P↓, and the semiconductor MoTe. First-principles calculations show robust ferroelectric polarization-controlled switching behavior between the high conductance state in configuration AA-P↓ and the low conductance state in configuration AA-P↑ in the most stable AA stacked vdWHs. Based on this vdWH, a two-dimensional transverse FTJ with AA-P↓ or AA-P↑ as the tunneling barrier and (InSn)Se monolayers (-type doped) as electrodes is designed. The tunneling electroresistance ratio of the FTJs at the Fermi level reaches 1.22 × 10% when the tunneling barrier contains two repeating units = 2 and can be greatly increased by increasing the thickness of the ferroelectric layer. Analysis of the work function, charge redistribution, and local density of states is performed to interpret the above phenomena. The findings suggest the great potential of the AA stacked α-InSe/MoTe vdWH in the design of high-performance FTJs and application in high-density non-volatile memory devices.