应力调控BlueP/XTe2(X=Mo,W)范德瓦耳斯异质结电子结构及光学性质理论研究

通过第一性原理计算探讨了蓝磷烯与过渡金属硫化物MoTe₂/WTe₂形成范德瓦耳斯异质结的电子结构和光学性质,以及施加双轴应力对相关性质的影响.计算结果表明,形成BlueP/XTe₂(X=Mo,W)异质结,二者能带排列为间接带隙type-Ⅱ并有较强的红外光吸收,同时屏蔽特性增强.随压缩应力增加,BlueP/XTe₂转变为直接带隙type-Ⅱ能带排列最后转变为金属性;随拉伸应力增加,异质结转变为间接带隙type-Ⅰ能带排列.外加应力也能有效调控异质结的光吸收性质,随压缩应力增加吸收边红移,光吸收响应拓展至中红外光谱区且吸收系数增大;BlueP/MoTe₂较BlueP/WTe₂在中红外至红外光区间表现出更强的光吸收响应;静态介电常数ε1(0)大幅增加.结果表明,压缩应力对BlueP/MoTe₂和BlueP/WTe₂能带排列、光吸收特性均有显著的调控作用,其中BlueP/MoTe₂对调控更敏感,这些特性也使BlueP/XTe₂异质结在窄禁带中红外半导体材料及光电器件具有令人期待的应用价值.

Tunable electronic structure and optical properties of BlueP/XTe2(X=Mo,W)van der Waals heterostructures by strain

First principles calculations are performed to explore the electronic structure and optical properties of BlueP/XTe₂,(X=Mo,W)van der Waals heterostructures after biaxial strain has been applied.The type-Ⅱband alignments with indirect band gap are obtained in the most stable BlueP/XTe₂,heterostructures,in which the photon-generated carriers can be effectively separated spatially.The BlueP/MoTe₂,and BlueP/WTe₂,heterostructures both have appreciable absorption of infrared light,while the shielding property is enhanced.The increase of biaxial compressive strain induces indirect-direct band gap transition and semiconductor-metal transition when a certain compressive strain is imposed on the heterostructures,moreover,the band gap of the heterostructures shows approximately linear decrease with the compressive strain increasing,and they undergo a transition from indirect band gap type-Ⅱto indirect band gap type-Ⅰ with the increase of biaxial tensile strain.These characteristics provide an attractive possibility of obtaining novel multifunctional devices.We also find that the optical properties of BlueP/XTe₂,heterostructures can be effectively modulated by biaxial strain.With the increase of compression strain,the absorption edge is red-shifted,the response of light absorption extends to the mid-infrared light and the absorption coefficient increases to 10^–5cm^–1for the two heterostructures.The BlueP/MoTe₂,shows stronger light absorption response than the BlueP/WTe₂,in the mid-infrared to infrared region and theε1(0),increases significantly.The BlueP/XTe₂,heterostructures exhibit modulation of their band alignment and optical properties by applied biaxial strain.The calculation results not only pave the way for experimental research but also indicate the great potential applications of BlueP/XTe₂,van der Waals heterostructures in narrow band gap mid-infrared semiconductor materials and photoelectric devices.