MoS_(2)和MoTe_(2)同质结和异质结中的表面电势排列  

Surface potential alignment in MoS_(2)and MoTe_(2)homo-and hetero-junctions

作　　者：江聪 张帅君 李玉莹 王文静 夏辉 李天信[2,3] JIANG Cong;ZHANG Shuai-Jun;LI Yu-Ying;WANG Wen-Jing;XIA Hui;LI Tian-Xin(College of Science,University of Shanghai for Science and Technology,Shanghai 200093,China;State Key Laboratory of Infrared Physics,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China;University of Chinese Academy of Sciences,Beijing 100049,China;Mathematics and Science College,Shanghai Normal University,Shanghai 200234,China)

机构地区：[1]上海理工大学理学院,上海200093 [2]中国科学院上海技术物理研究所红外物理国家重点实验室,上海200083 [3]中国科学院大学,北京100049 [4]上海师范大学数理学院,上海200234

出　　处：《红外与毫米波学报》2023年第6期743-747,共5页Journal of Infrared and Millimeter Waves

基　　金：Supported by the National Natural Science Foundation of China(11991063,62004207,61725505,62104118);the Shanghai Science and Technology Committee(2019SHZDZX01,19XD1404100,20YF1455900,20ZR1474000);the Strategic Priority Research Program of Chinese Academy of Sciences(XDB43010200);the Youth Innovation Promotion Association CAS(2018276)。

摘　　要：过渡金属硫族化合物(TMD)薄层仅改变几何形状(如层厚)就可调节带隙、电子亲和势和费米能级,使器件设计更灵活。但因缺乏费米能级排列信息,TMD同质/异质结器件常因未知的能带弯曲而偏离预期。利用扫描开尔文探针显微镜(SKPM)表征了TMD同质/异质结,结果显示,Mo S_(2)和Mo Te_(2)同质结的费米能级随层厚增加向本征费米能级移动(背景掺杂浓度降低),而Mo Te_(2)/Mo S_(2)异质结中探测到宽耗尽区和强光响应,同时给出表面污染(分子尺度)对单层TMD表面电势的影响。上述发现将在器件设计中帮助精准堆叠范德华(vdW)层。In transition metal dichalcogenides(TMD)flakes,the geometry,such as layer thickness,significant⁃ly tune the electronic properties,including bandgap,electron affinity and Fermi level.Such characteristic offers a high degree of freedom to tune the functionality of semiconductor device,once the volatile electronic properties are precisely determined.However,to date,there are still significant uncertainties in determining the Fermi-level alignment of TMD homo-or hetero-junctions,which might lead to significant deviations of band-bending and thus device performance.Here,we utilize the Scanning Kelvin Probe Microscopy(SKPM)to characterize the surface-potential/Fermi-level alignment of TMD homo-or hetero-junctions.Through this effort,a distinct phe⁃nomenon is verified where the Fermi-levels of MoS_(2)and MoTe_(2)shift towards the intrinsic level with an increasing layer thickness(in other words,the background doping concentration is continuously lowering).Moreover,we show the significant impact of surface contamination(molecular scale)on the surface potential of monolayer TMD.Finally,we fabricate a MoTe_(2)/MoS_(2)heterojunction,in which we observe the wide depletion region and large photoresponse.Together,those findings might offer a reference to precisely stack van der Waals(vdW)lay⁃ers as designed for both electronic and optoelectronic applications.

关 键 词：表面电势 过渡金属硫族化合物(TMD) 扫描开尔文探针显微镜(SKPM) 层厚 

分 类 号：O472.1[理学—半导体物理]