褶皱状单层GeSe各向异性的能带漏斗效应  

Anisotropic energy funneling effect in wrinkled monolayer GeSe

作　　者：刘俊杰 左慧玲 谭鑫 董健生 Liu Jun-Jie;Zuo Hui-Ling;Tan Xin;Dong Jian-Sheng(College of Physics and Electromechanical Engineering,Jishou University,Jishou 416000,China)

机构地区：[1]吉首大学物理与机电工程学院,吉首416000

出　　处：《物理学报》2024年第23期176-183,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12364007);湖南省研究生科研创新项目(批准号:CX20240945);湖南省大学生创新创业训练项目(批准号:S202310531036);国家级大学生创新创业训练项目(批准号:S202410531045)资助的课题.

摘　　要：褶皱结构引起的周期性连续变化应变为调控二维材料电子和光电性质提供了重要手段.然而,关于褶皱状二维材料的形成机理及其对相关物性的调控研究仍缺乏理解.本文基于原子键弛豫理论和连续介质力学方法,系统研究了褶皱状单层GeSe能带结构随波长和位置的变化规律.结果表明,由于各向异性的力学性质和褶皱引起的周期性连续变化应变,褶皱状单层GeSe表现出各向异性的能带漏斗效应,激子会定向聚集在褶皱的谷区域,且聚集能力随着波长的减小而增强.此外,当波长减小至106 nm,锯齿型褶皱状单层GeSe的能带漏斗消失,而扶手椅型褶皱状单层GeSe的能带漏斗依然得以保持.这些结果为褶皱状单层GeSe在激子输运中的应用提供了理论基础,并为设计高性能基于二维材料的光电器件提供了新策略.Two-dimensional materials with tunable wrinkled structures open up a new way to modulate their electronic and optoelectronic properties.However,the mechanisms of forming wrinkles and their influences on the band structures and associated properties are still unclear.Here,we investigate the strain distribution,bandgap,and anisotropic energy funneling effect of wrinkled monolayer GeSe and their evolution with the wrinkle wavelength based on the atomic-bond-relaxation approach and continuum medium mechanics.We find that the top region and valley region of wrinkled monolayer GeSe exhibit tensile and compressive strains,respectively,and the strain increases with wrinkle wavelength decreasing.Moreover,the periodic undulation strain in the wrinkles can lead to continuously adjustable bandgaps and band edges in wrinkled monolayer GeSe.For zigzag wrinkled monolayer GeSe,when the wrinkle wavelength is long,the conduction band minimum value(valence band maximum value)continuously decreases(increases)from the top to the valley,forming an energy funnel.As a result,the excitons accumulate in the valleys of wrinkles,and their accumulation capability increases with wrinkle wavelength decreasing.However,as the wavelength further decreases,the energy funnel will disappear,causing some excitons to t accumulate at the top of wrinkles,while the remaining excitons will accumulate in the valleys of wrinkles.The critical wavelength for the energy funnel of zigzag wrinkled GeSe to disappear is 106nm.The physical origin is that when the top strain exceeds 4%,the bandgap will decrease.Owing to the monotonic variation of bandgap with strain,the energy funneling effect of armchair wrinkled monolayer GeSe is still retained when the wavelength decreases to 80 nm,and the accumulation of excitons is further enhanced.Our results demonstrate that the energy funneling effect induced by nonuniform can realize excitons’accumulation in one material without the need of p-n junctions,which is of great benefit to the collection of photogenerated excito

关 键 词：GeSe 褶皱结构 能带漏斗效应 原子键弛豫理论 

分 类 号：TB34[一般工业技术—材料科学与工程] O469[理学—凝聚态物理]