Quantum Transport Simulations Of A Two-Dimensional SnSe Ferroelectric Semiconductor Junction

The architecture of in memory computing can achieve the integration of computing and storage,which breaks through the constraints of the"power wall" and "storage wall" under the von Neumann architecture.Ferroelectric memristor has the characteristics of high speed,low power consumption,nonvolatile,and controllable polarization state,etc.It can simultaneously calculate and store data in a single computing unit.Meanwhile,two-dimensional devices have the characteristics of miniaturization and easy regulation.Therefore,the two-dimensional ferroelectric memristor has received more and more attention and expectations from researchers.Researchers found that two-dimensional In2Se3 material has both in-plane and out of plane ferroelectric polarization,and designed electronic devices accordingly.Two dimensional ferroelectric semiconductors such as two-dimensional SnSe and two-dimensional SnTe were predicted by researchers to have in-plane ferroelectric polarization and were successfully prepared experimentally.Due to its combination of semiconducting bandgap and non-volatile ferroelectricity,two-dimensional SnSe materials are considered as potential platforms for the next generation of storage computing devices.In order to explore the potential of two-dimensional SnSe materials in the integration of storage and computing,we studied the electronic properties and ferroelectricity of two-dimensional SnSe materials based on the first principle calculation,and designed a two-dimensional ferroelectric semiconductor junction and simulated the transport performance of the device.A computational array based on SnSe material has been designed.The main research achievements are as follows:(1)It is confirmed that the two-dimensional SnSe material is a semiconductor material with 1.53 eV indirect band gap.There is in-plane ferroelectric polarization,and the polarization direction is along the armchair direction.(2)A two-dimensional ferroelectric semiconductor junction with SnSe as the channel and graphene as the electrode is designed.It is found that the in-plane ferroelectricity of SnSe makes the electronic structure of the interface composed of SnSe and graphene directional dependent,and the corresponding devices show a natural asymmetric output characteristic curve under positive and negative voltage without doping.The device exhibits current densities of 248 A/m and 10 A/m under applied bias voltages of-0.9 V and+0.9 V,respectively.(3)In the design of computing array,we set the in-plane polarization of SnSe through bias voltage,and the computing unit composed of two SnSe ferroelectric memristor can further realize different logic computing functions such as OR,NAND and XNOR,and further realize logic functions such as half-adder.Compared with the traditional gate circuit,the number of transistors or memristor required for this SnSe based computing array to achieve the same function is significantly reduced.Our research provides a new approach for utilizing two-dimensional ferroelectric semiconductors to achieve integrated storage and computing functions.