石墨烯/C_(3)N范德瓦耳斯异质结的可调电子特性和界面接触  

Tunable electronic structures and interface contact in graphene/C_(3N) van der Waals heterostructures

作　　者：黄敏 李占海 程芳[1] Huang Min;Li Zhan-Hai;Cheng Fang(School of Physics and Electronic Science,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学物理与电子科学学院,长沙410114

出　　处：《物理学报》2023年第14期226-235,共10页Acta Physica Sinica

基　　金：柔性电子材料基因工程湖南省重点实验室和长沙理工大学研究生科研创新项目(批准号:CXCLY2022148)资助的课题。

摘　　要：基于石墨烯的范德瓦耳斯异质结既可以调节石墨烯的电子特性,还可以保留原始单层材料的优越特性.利用第一性原理,本文系统地研究了石墨烯/C_(3)N范德瓦耳斯异质结的结构、电接触类型及光学性质.研究表明,平衡态下异质结中存在仅为0.039 eV的准p型欧姆接触.外加电场能调控异质结界面的接触类型,实现p型肖特基接触到欧姆接触的转变.垂直应变可以同时调控石墨烯和C_(3)N的投影能带,甚至为石墨烯打开了一个不可忽视的带隙(360 meV).外加电场和施加垂直应变这两种物理方法都能对异质结中石墨烯层的载流子掺杂类型和浓度进行有效调制.石墨烯层的载流子掺杂浓度的增大通过电场的调制更显著.与单层石墨烯和C_(3)N相比,两者构成的范德瓦耳斯异质结的光学响应范围和光吸收率均得到了提高.光谱中的主吸收峰高达10^(6) cm^(-1).这些结果不仅为基于石墨烯/C_(3)N范德瓦耳斯异质结器件的设计提供了有价值的理论指导,还为异质结在光电纳米器件和场效应晶体管器件应用提供了新的思路和设计.Graphene-based van der Waals heterojunctions can not only modulate the electronic properties of graphene but also retain the superior properties of the original monolayer.In this paper,the structure,electrical contact types,electronic and optical properties of graphene/C_(3)N van der Waals heterojunctions are systematically investigated based on first-principles calculations.We find that there is a p-type Schottky contact of only 0.039 eV in the graphene/C_(3)N van der Waals heterojunctions in an equilibrium state.The external electric field can adjust the interface contact type,specifically,from p-type to n-type Schottky contact,or from p-type Schottky contact to Ohmic contact.The vertical strain not only opens a nonnegligible band gap of 360 meV on the Dirac cone of graphene in graphene/C_(3)N van der Waals heterojunctions,but also modulates the band gap of C_(3)N in the heterojunctions.Moreover,both the doping type and concentration of the carriers can be effectively tuned by the applied electric field and the vertical strain.The increase in carrier concentration is more pronounced by the applied electric field.Comparing with the pristine monolayer graphene and monolayer C_(3)N,the optical response range and the light absorption rate of graphene/C_(3)N van der Waals heterojunctions are enhanced.Main absorption peak in the spectrum reaches to 10~6 cm^(-1).These results not only provide valuable theoretical guidance for designing Schottky-based graphene/C_(3)N van der Waals heterojunctions devices,but also further explore the potential applications of heterojunctions in optoelectronic nanodevices and field-effect transistor devices.

关 键 词：范德瓦耳斯异质结 肖特基接触 欧姆接触 电接触 

分 类 号：TB332[一般工业技术—材料科学与工程] O469[理学—凝聚态物理]