【摘要】 基于铁电Rashba半导体的自旋场效应晶体管具有比普通晶体管更短的通道长度,是未来晶体管的重要类型.采用高通量逆向设计,AlBi和SiPb单层被认为是极具潜力的铁电Rashba半导体候选材料,因为二者不仅具有显著的Rashba效应和超薄的原子结构,还能够克服能量势垒.本文采用第一性原理计算,系统研究了AlBi和SiPb单层中的Rashba效应、电场响应和铁电性的调控.结果表明,AlBi和SiPb单层的Rashba系数分别为2.717和2.606 eV.??,可以通过外加电场和应变进行有效调控;AlBi的电场响应强度约为0.5 eV.??~2,SiPb的电场响应强度可以达到0.78 eV.??~2,完全满足实际应用的要求.此外,AlBi和SiPb是典型的二维铁电材料,其铁电极化与自旋极化的耦合效应也进一步被探究.基于这些研究结果,设计了两种以AlBi(SiPb)单层作为通道材料的自旋场效应晶体管.如果仅考虑材料的电场响应而不考虑其铁电性,设计的晶体管通道长度为70～100 nm之间;而基于铁电性设计的自旋场效应晶体管可以将通道长度减小至2 nm以下,远低于半导体中相干输运的容忍限度.因此,二维铁电Rashba半导体被认为是下一代自旋场效应晶体管的有力候选材料.更多还原

【Abstract】 The spin field-effect transistor(SFET)based on ferroelectric Rashba semiconductor(FRS) has a shorter channel length than ordinary transistors,making it an important type of future transistor.Through high-throughput inverse design,AlBi and SiPb monolayers are considered to be very promising FRSs due to their prominent Rashba effect,the thinnest atomic structure,and surmountable energy barriers.Herein,we employ first-principles calculations to systematically investigate the modulation of Rashba effect,electric field response,and ferroelectricity in AlBi and SiPb monolayers.The large Rashba coefficients of 2.717 and 2.606 eV·?? are obtained for AlBi and SiPb monolayers,while they can be efficiently modulated by the external electric field and strain engineering.The electric field response of AIBi oscillates around 0.5 e· ??~2 and that of SiPb can reach 0.78 e·??~2,which can fully meet the requirements of practical applications.Furthermore,as typical two-dimensional ferroelectric materials,the coupling effect between ferroelectric polarization and spin polarization is also explored.Based on these investigations,we design two types of SFET with AlBi or SiPb monolayer as the channel.The SFET designed solely based on the electric field response without considering the ferroelectricity,has a channel length ranging from 70 nm to 100 nm.The SFET designed based on the ferroelectricity can reduce the channel length to below 2 nm,which is quite below the tolerance of coherent transport in semiconductors.Thus,two-dimensional(2D) FRS can be considered as a promising candidate material for the next generation of SFETs.更多还原