尺寸效应对MoS2/WSe2范德华异质结构层间与俄歇复合的界面调控

Size Effect on the Interface Modulation of Interlayer and Auger Recombination Rates in MoS2/WSe2 van der Waals Heterostructures

为探索界面工程对二维材料范德华异质结构中载流子复合率的影响,本工作基于界面键弛豫理论和费米黄金定则,建立了范德华异质结俄歇和层间复合率与各结构组元尺寸之间的理论模型。结果表明,MoS2/WSe2异质结的俄歇复合寿命随着组元尺寸的增大而增加,且异质结的俄歇复合率远小于相应的单组元体系。在MoS2/WSe2双层异质结中引入薄h-BN插层后,体系的层间复合率和俄歇复合率随h-BN厚度的增加而分别呈现减小和增大的趋势;在组元处于单层MoS2和WSe2情况下,当界面插层h-BN厚度达到9.1 nm时,俄歇复合率将趋于5.3 ns^-1。该研究结果为二维过渡金属硫族化合物基异质结光电器件的优化设计提供了一种理论依据。

To explore the interface engineering on the carrier recombination in two-dimensional(2D)van der Waals(vdW)heterostructures,we developed a theoretical model to address the size-dependent interlayer and Auger recombination rates in MoS2/WSe2 in terms of interface bond relaxation method and Fermi's golden rule.It is found that the Auger recombination lifetime in MoS2/WSe2 increases with increasing thickness due to the weakening of Coulomb interaction between holes and electrons,as well as the Auger recombination rate is much smaller than that of MoS2 and WSe2 units.However,when the thin h-BN layer is introduced into the MoS2/WSe2,the interlayer and Auger recombination rates show opposite trends as the h-BN thickness increases.When the thickness of h-BN reaches 9.1 nm under the condition of 1L MoS2/h-BN/1L WSe2,the Auger recombination rate approaches 5.3 ns^-1.These results indicate that the relevant recombination processes can be tuned by interface and dimension.Therefore,our results provide a useful guidance for the optimal design of 2D transition metal dichalcogenides-based optoelectronic nanodevices.