Transfer-free, scalable vertical heterostructure FET on MoS2/WS2continuous films

Merve Acar; Mehmet Ertuğrul; Emre Gür

doi:10.1088/1361-6528/ac8997

Transfer-free, scalable vertical heterostructure FET on MoS₂/WS₂continuous films

Nanotechnology. 2022 Aug 31;33(47). doi: 10.1088/1361-6528/ac8997.

Authors

Merve Acar¹, Mehmet Ertuğrul^{1

2}, Emre Gür^{2

3}

Affiliations

¹ Department of Electrical and Electronics Engineering, Faculty of Engineering, Atatürk University, 25240, Erzurum, Turkey.
² Department of Nanoscience and Nanotechnology, Graduate School of Natural and Applied Sciences, Ataturk University, 25240 Erzurum, Turkey.
³ Department of Physics, Faculty of Science, Atatürk University, 25240, Erzurum, Turkey.

PMID: 35970141
DOI: 10.1088/1361-6528/ac8997

Abstract

Taking into account the novel layered structure and unusual electronic properties of MoS₂and WS₂on the side the lack of dangling bonds between these two components and donor-acceptor linkage effects, growth of the MoS₂/WS₂vertical heterojunction film on the amorphous SiO₂/Si substrate have created high demand. In this study, we reported the continuous, scalable, and vertical MoS₂/WS₂heterostructure film by using a sputtering without a transfer step. The WS₂film was continuously grown on MoS₂and eventually led to the formation of the MoS₂/WS₂vertical heterojunction film. Dozens of FETs fabricated on MoS₂/WS₂continuous heterojunction film were created on the same substrate in a single lithographic fabrication step, allowing them to be commercialized and not only used in research applications. RAMAN spectra proved the formation of the MoS₂/WS₂heterostructure film. In XPS measurements, it was shown that a separate MoS₂and WS₂layer was grown instead of the alloy structure. The polarity behavior of the MoS₂/WS₂heterostructure FET was found to be modulated with different drain voltages as p-type to ambipolar and finally n-type conductivity because of the transition of band structure and Schottky barrier heights at different drain voltages. Electron mobility (7.2 cm²V.s^-1) and on/off ratio (10⁴-10⁵) exhibited by the MoS₂/WS₂heterostructure FETs displayed a more improved electrical performance than that of individual WS₂, MoS₂devices. It was observed that the mobility value of MoS₂/WS₂FET was approximately 514 times greater than WS₂FET and 800 times greater than MoS₂FET. Additionally, the MoS₂/WS₂FET on/off ratio was larger than 2 order MoS₂FET and 1 order WS₂FET. The film of continuous vertical heterojunctions as in the MoS₂/WS₂currents in the study would be a promising candidate for nanoelectronics fields. This work demonstrated the progress towards realizing carrier-type controlled high-performance MoS₂/WS₂heterojunction-based FETs for future logic devices.

Keywords: 2D heterostructures; MoS2; TMDC; WS2; ambipolar FET; sputtering.