Transfer-free, scalable vertical heterostructure FET on MoS2/WS2continuous films
Merve Acar1, Mehmet Ertuğrul1,2, Emre Gür2,3
1Department of Electrical and Electronics Engineering, Faculty of Engineering, Atatürk University, 25240, Erzurum, Turkey.
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.
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