Transfer-free, scalable vertical heterostructure FET on MoS2/WS2 continuous films

Abstract

Abstract Taking into account the novel layered structure and unusual electronic properties of MoS2 and WS2 on the side the lack of dangling bonds between these two components and donor–acceptor linkage effects, growth of the MoS2/WS2 vertical heterojunction film on the amorphous SiO2/Si substrate have created high demand. In this study, we reported the continuous, scalable, and vertical MoS2/WS2 heterostructure film by using a sputtering without a transfer step. The WS2 film was continuously grown on MoS2 and eventually led to the formation of the MoS2/WS2 vertical heterojunction film. Dozens of FETs fabricated on MoS2/WS2 continuous 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/WS2 heterostructure film. In XPS measurements, it was shown that a separate MoS2 and WS2 layer was grown instead of the alloy structure. The polarity behavior of the MoS2/WS2 heterostructure 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 cm2 V.s−1) and on/off ratio (104–105) exhibited by the MoS2/WS2 heterostructure FETs displayed a more improved electrical performance than that of individual WS2, MoS2 devices. It was observed that the mobility value of MoS2/WS2 FET was approximately 514 times greater than WS2 FET and 800 times greater than MoS2 FET. Additionally, the MoS2/WS2 FET on/off ratio was larger than 2 order MoS2 FET and 1 order WS2 FET. The film of continuous vertical heterojunctions as in the MoS2/WS2 currents in the study would be a promising candidate for nanoelectronics fields. This work demonstrated the progress towards realizing carrier-type controlled high-performance MoS2/WS2 heterojunction-based FETs for future logic devices.