摘要
二维过渡金属二硫化物(transition metal dichalcogenides,TMDCs)因其原子级平坦的表面、可调的能带结构等优势而在光学、电学、热学等领域受到广泛关注,并且为解决传统硅基晶体管尺寸进一步微缩面临的挑战提供了新的机遇.能带工程是调控二维TMDCs材料电子结构并研究其物理学特性的重要手段.本文从本征调控和外部调控两个方面综述了近年来二维TMDCs材料中的能带调控策略,主要包括本征层数调控、零维点缺陷调控(晶格空位构筑、掺杂/合金化)、施加应变、构筑异质结等.在现有研究成果的基础上,对未来的研究方向进行了展望.
optoelectronics,due to the atomically thin surface,tunable energy band,etc.2D TMDCs also provide new opportunities to solve the challenge of further shrinking the size of traditional silicon-based transistors.Energy band engineering is an important strategy to modulate the properties of 2D TMDCs.In this contribution,we highlight the recent progress in the energy band engineering of 2D TMDCs based on two aspects:Intrinsic and extrinsic modulations.The energy band engineering strategies mainly include intrinsic layer-number modulation,zero-dimensional point defects modulation(e.g.,vacancy,dopants/alloy),applying strain,constructing heterostructures,etc.In addition to constructing 2D TMDCs heterostructures,inducing heteroatoms to construct alloy heterostructures can achieve continuously tunable energy band structures,providing more possibilities toward the enhanced functionalities.Thus,combination of one or more strategies to modulate the energy band of 2D TMDCs can provide more freedom and approaches,such as vacancy-doping/alloy,vacancy-strain,etc.The detailed energy band engineering strategies in 2D TMDCs can be summarized as follows:(1)Considering the limitations of mechanical exfoliation to prepare 2D TMDCs materials with different layers(e.g.,poor controllability,small size),the layer-number tunable strategy of 2D TMDCs materials can be achieved by chemical vapor deposition(CVD)route,which can tune various growth parameters,such as precursors,growth temperature and time,carrier gas,additive,etc.,to control the layer numbers of as-grown 2D TMDCs.(2)About the vacancy tunable strategy,high-energy particle impact,plasma treatment and annealing under the inert atmosphere are widely used to produce vacancies in 2D TMDCs lattice.The challenge is that how to produce the vacancies with uniform distribution,controllable concentrations and configurations by a precise and repeatable route.(3)Compared with physical absorption doping,substitutional doping heteroatoms into 2D TMDCs lattices is a much more stable and controllable strategy.In order to achieve the uniform distributions of heteroatoms in 2D TMDCs lattices,water-solution precursor and spin-coating can be used to grow doped 2D TMDCs materials by CVD routes and exhibit excellent controllability and tunability with different doping concentrations.While,dual-heteroatom doping strategy is also demonstrated by our group to further improve the optical performance of TMDCs materials.(4)In terms of the excellent mechanical properties of 2D TMDCs,strain engineering is also widely used to tune their energy band.And,2D TMDCs materials can stand much more strain than their bulk counterparts.The introduction of strain in 2D TMDCs strain can be divided into two categories:Transfer the target 2D TMDCs into flexible substrates or rough substrates and design specific substrates during growth.(5)2D TMDCs materials offer the unique integration tunability to further boost their performance,especially for constructing heterostructures,including in-plane and out-of-plane heterostructures.According to the band alignment configurations,2D TMDCs heterostructures can be divided into three types:In type-I heterostructure,the energy band of one kind of TMDCs is completely located within that of the other kind of TMDCs,which can be used for light-emitting devices;in type-II heterostructure,the energy bands of two kinds of TMCDs are overlapped,which can be applied in photodetectors and photovoltaic devices;in type-III heterostructures,the energy bands of two kinds of TMDCs are non-overlapped and can be used to design high-speed,low-power devices.In order to achieve the continuous modulation of energy bands in heterostructures,alloy heterostructures with composition gradient at the interfaces are synthesized.Our group has synthesized monolayer MoSe2-WSe2 in-plane heterostructures with slightly doping at the zigzag interfaces.The fabricated suspend H-type device using MoSe2-WSe2 in-plane heterostructures exhibits high electrical(104)and thermal(96%)rectification effects,benefiting from the higher matched phonon spectra in the J+from MoSe2 to WSe2 direction than that in the J–from WSe2 to MoSe2 direction and zigzag interface configurations with slightly localized doping.The high thermal rectification of monolayer MoSe2-WSe2 in-plane heterostructures provides an alternative way to solve the heat dissipation problem caused by the high integration in chip industry.Finally,based on the recent research progress,the research directions for the energy band modulation of 2D TMDCs in the future are proposed.
作者
吕倩
马翰原
吕瑞涛
Qian Lü;Hanyuan Ma;Ruitao Lü(Key Laboratory of Advanced Materials(Ministry of Education),School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;State Key Laboratory of New Ceramics and Fine Processing,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2023年第14期1829-1843,共15页
Chinese Science Bulletin
基金
国家重点研发计划(2021YFA1200803)
国家自然科学基金(51972191)资助。
关键词
二维材料
过渡金属二硫化物
能带调控
物理特性
two-dimensional materials
transition metal dichalcogenides
energy band engineering
physical properties
