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Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy
Journal article   Peer reviewed

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, …
Nanoscale, Vol.14, pp.8260-8270
21/06/2022
DOI: https://doi.org/10.1039/d2nr01504h
PMID: 35660824

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Abstract

Chemistry Chemistry, Multidisciplinary Materials Science Materials Science, Multidisciplinary Nanoscience & Nanotechnology Physical Sciences Physics Physics, Applied Science & Technology Science & Technology - Other Topics Technology
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 omega mu m and 54.9 omega mu m, 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 (phi(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.

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