结构相变引起单层RuSe2载流子迁移率的提高
Structural phase transition induced enhancement of carrier mobility of monolayer RuSe2
陆康俊 1王一帆 1夏谦 1张贵涛 1陈乾1
作者信息
- 1. 东南大学物理学院,量子材料与信息器件教育部重点实验室,南京 211189
- 折叠
摘要
过渡金属二硫族化合物(TMDs)是二维材料家族中的重要成员,具有丰富多样的晶体结构和物理特性,是近年来在科学研究和器件应用领域关注度较高的材料之一.本文通过第一性原理计算研究了单层RuSe2的结构和相变,在确定其基态为二聚相(T′相)的同时,发现该材料存在能量相近的三聚相(T(''')相).分别从动力学和热力学角度预测了该晶相结构的稳定性.结合相变势垒的计算和分子动力学模拟,预测在室温下对T′相结构施加较小的应力就可以实现晶格从T′相到T(''')相的转变.相变后的能带结构以及载流子迁移率都发生了明显的改变,其带隙由1.11 eV的间接带隙转变为0.71 eV的直接带隙,载流子迁移率有了大幅的提升,空穴迁移率达到了 3.22 × 103cm2·V-1·s-1.本文对比研究了 RuSe2单层中可能共存的两种畸变相,分析了不同晶相的电子结构和迁移率,为实验上研究二维RuSe2材料及其在未来器件中的应用提供了理论依据.
Abstract
Transition metal dichalcogenides(TMDs)is an important member of two-dimensional material family,which has various crystal structures and physical properties,thus providing a broad platform for scientific research and device applications.The diversity of TMD's properties arises not only from their relatively large family but also from the variety of their crystal structure phases.The most common structure of TMD is the trigonal prismatic phase(H phase)and the octahedral phase(T phase).Studies have shown that,in addition to these two high-symmetry phases,TMD has other distorted phases.Distorted phase often exhibits different physical properties from symmetric phases and can perform better in certain systems.Because the structural differences between different distorted phases are sometimes very small,it is experimentally challenging to observe multiple distorted phases coexisting.Therefore,it is meaningful to theoretically investigate the structural stability and physical properties of different distorted phases.In this study,we investigate the structure and phase transition of monolayer RuSe2 through first-principles calculation.While confirming that its ground state is a the dimerized phase(T′phase),we find the presence of another energetically competitive trimerized phase(T(''')phase).By comparing the energy values of four different structures and combining the results of phonon spectra and molecular dynamics simulations,we predict the stability of the T(''')phase at room temperature.Because the H phase and T phase of two-dimensional RuSe2 have already been observed experimentally,and considering the fact that T(''')phase has much lower energy than the H and T phases,it is highly likely that the T(''')phase exists in experiment.Combining the calculations of the phase transition barrier and the molecular dynamics simulations,we anticipate that applying a slight stress to the T′phase structure at room temperature can induce a lattice transition from T′phase to T(''')phase,resulting in significant changes in the band structure and carrier mobility,with the bandgap changing from an indirect bandgap of 1.11 eV to a direct bandgap of 0.71 eV,and the carrier mobility in the armchair direction increasing from 0.82× 103 cm2·V-1·s-1 to 3.22 × 103 cm2·V-1·s-1,an approximately threefold enhancement.In this work,two possible coexisting distorted phases in monolayer RuSe2 are compared with each other and studied,and their electronic structures and carrier mobilities are analyzed,thereby facilitating experimental research on two-dimensional RuSe2 materials and their applications in future electronic devices.
关键词
二硒化钌/结构相变/载流子迁移率/第一性原理计算Key words
RuSe2/phase transition/carrier mobility/first-principles calculation引用本文复制引用
基金项目
国家重点研发计划(2022YFA1503103)
国家自然科学基金(22033002)
江苏省研究生科研创新计划(KYCX23_0223)
出版年
2024
国家科技期刊平台
NSTL
万方数据