High-Quality CVD-MoS2 Synthesized on Surface-Modified Al2O3 for High-Performance MoS2 Field-Effect Transistors

In this article, an effective way of chemical modificationon the dielectric surface (Al2O3) is investigated to chemical vapor deposition (CVD)-grown high-quality monolayer MoS2 and the relevant back- gated FETs are fabricated without MoS2 transfer. As a result, the size of the triangleMoS2 is increased and its quality is improved as the surface of Al2O3 is treated by H2SO4. Furthermore, as compared with the gate dielectrics of the SiO2 and as-deposited Al2O3, the fabricated transistor with the H2SO4-treated Al2O3 as gate dielectric achieves better electrical properties: high carrier mobility of 12.9 cm2/Vs (similar to 10 times higher than the untreated sample, similar to 5.2 times higher than the SiO2 gate-dielectric sample), small subthreshold swing of 110 mV/dec, and high ON/OFF ratio of 3 x 106. The involved mechanisms are attributed to the fact that theH2SO4-treated Al2O3 not only can increase its surface roughness to promote the nucleation and high-quality growth of MoS2 but also can improve the quality of the MoS2/Al2O3 interface. This simple chemical-modification treatment will open up an effective approach of combining the high-crystallinity CVD-MoS2 with the high- k dielectric without MoS2 transfer required.