Study On The First Principle Of Phase Change Superlattice Materials Based On BiSbTe

Phase change memory(PCM),as a new non-volatile memory,has the advantages of fast read-write speed,high storage density,anti-radiation,multilevel storage and so on.Phase change memory cells can not only replace traditional memory cells,but also become a strong competitor of neuromorphological computing chips.However,phase change speed,operation power consumption and thermal crosstalk of PCM are important factors that affect the performance of PCM.By looking for new phase change memory materials,the performance of phase change memory can be optimized,and the phase change superlattice material is one of main research directions.This paper is based on Bi₂Te₃ and Sb₂Te₃,two commom phase change materials,by using the first-principle calculation simulation method,the change of crystal structure and electronic structure before and after the formation of superlattices,and the effects of component,lattice strain,atomic vacancy and atomic sequence on the properties of superlattices were studied.At last,we sum up the formation rules of electronic structure of this kind of superlattice materials.The results of research show that:1.The bandgap of the quintuple layer of the Bi₂Te₃ and Sb₂Te₃ is larger than that of the bulk material,which is attributed to micro energy band produced by coupling of atoms at the Vander Waals interface.2.Most of the(Bi₂Te₃)_m/(Sb₂Te₃)_n heterojunctions show good lattice matching,and different component ratio cause different bandgap.3.By applying the lattice strain,it is found that changing the Vander Waals interface spacing can adjust the microstrip,so as to adjust the bandgap.4.The vacancy of Bi(Sb)atom can adjust the number of Vander Waals interface and enhance the conductivity;while the vacancy of Te atom at the interface is easy to produce the defect energy level and weaken the conductivity.5.The inversion of Bi(Sb)-Te sequence at the Vander Waals interface can lead to the decrease of the surface spacing or the imbalance of the stoichiometric,which can improve the conductivity of the crystal.In this paper,we use the lattice strain to adjust the Vander Waals Gap and component types of phase change superlattice to achieve the purpose of adjusting its electronic structure,which provides theoretical guidance for construction of phase change memory materials that meet the performance requirements.