Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy

Linglong Zhang; Yilin Tang; Han Yan; Tanju Yildirim; Shunshun Yang; Haizeng Song; Xiaowei Zhang; Fuguo Tian; Zhongzhong Luo; Jiajie Pei; Qi Yang; Yixin Xu; Xiaoying Song; Ahmed Raza Khan; Sihao Xia; Xueqian Sun; Bo Wen; Fei Zhou; Weiwei Li; Youwen Liu; Han Zhang

doi:10.1039/D2NR01504H

Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy†

Linglong Zhang,‡*^a Yilin Tang,‡^b Han Yan,‡^c Tanju Yildirim,^d Shunshun Yang,

^a Haizeng Song,^e Xiaowei Zhang,

^f Fuguo Tian,^a Zhongzhong Luo,^g Jiajie Pei,^h Qi Yang,ⁱ Yixin Xu,^a Xiaoying Song,^j Ahmed Raza Khan,^bk Sihao Xia,^a Xueqian Sun,^b Bo Wen,

*^l Fei Zhou,*^mn Weiwei Li,

*^a Youwen Liu^a and Han Zhang

ⁱ

Author affiliations

* Corresponding authors

^a College of Physics, Nanjing University of Aeronautics and Astronautics, Key Laboratory of Aerospace Information Materials and Physics (NUAA), MIIT, Nanjing 211106, China
E-mail: linglongzhang1@126.com, wl337@nuaa.edu.cn

^b Research School of Electrical, Energy and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra 2601, Australia

^c Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK

^d Center for Functional Sensor & Actuator (CFSN), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan

^e School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China

^f Department of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China

^g College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Jiangsu Province Engineering Research Center for Fabrication and Application of Special Optical Fiber Materials and Devices, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210023, China

^h College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, Fujian, China

ⁱ Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen, China

^j College of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing, China

^k Department of Industrial and Manufacturing Engineering University of Engineering and Technology (Rachna College), Lahore 54700, Pakistan

^l Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China
E-mail: dr.bowen1986@outlook.com

^m National Key Laboratory for Precision Hot Processing of Metals; School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
E-mail: angel.flyfly@hotmail.com

ⁿ State Key Laboratory for Environment-friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang, China

Abstract

Monolayer transition metal dichalcogenides (mTMDs) possess a direct band gap and strong PL emission that is highly sensitive to doping level and interfaces, laying the foundation for investigating the contact between mTMD and metal via PL spectroscopy. Currently, electrical methods have been utilized to measure the contact resistance (R_C), but they are complicated, time-consuming, high-cost and suffer from inevitable chemical disorders and Fermi level pinning. In addition, previously reported contact resistances comprise both Schottky barrier and tunnel barrier components. Here, we report a simple, rapid and low-cost method to study the tunnel barrier dominated contact resistance of mTMD based junctions through PL spectroscopy. These junctions are free from chemical disorders and Fermi level pinning. Excluding the Schottky barrier component, solely tunnel barrier dominated contact resistances of 1 L MoSe₂/Au and 1 L MoSe₂/graphene junctions were estimated to be 147.8 Ω μm and 54.9 Ω μm, respectively. Density functional theory (DFT) simulations revealed that the larger R_C of the former was possibly due to the existence of intrinsic effective potential difference (Φ_barrier) between mTMD and metal. Both junctions exhibit an increasing tendency of R_C as temperature decreases, which is probably attributed to the thermal expansion coefficient (TEC) mismatch-triggered interlayer spacing (d) increase and temperature-induced doping. Remarkably, a significant change of R_C was observed in 1 L MoSe₂/Au junctions, which is possibly ascribed to the changes of their orbital overlaps. Our results open new avenues for exploring fundamental metal–semiconductor contact principles and constructing high-performance devices.

Nanoscale

Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy†

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Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy

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