In recent years, due to the intriguing electrical and optical characteristics, two dimensional layered transition metal dichalcogenides such as MoS2 have attracted tremendous research attention. In a distinct contrast to the bandgap issue of graphene, MoS2 is semiconducting with a satisfied thickness-dependent bandgap of 1.2 to 1.8 eV, which can enable lots of fascinating device applications. However, until now, majority of the efforts have been focused on the integration of MoS2 devices in the back- or dual-gated geometry due to the difficulty of compact and conformal top-gated dielectric deposition directly onto the 2-D channel for the realization of high-performance top-gated FETs. In this regard, interface or dielectric engineering is an important step towards the practical implementation of MoS2 devices with the optimized performance.

In this work, we explore the case of interface engineering further by utilizing an ultrathin metal oxide (MgO, Al2O3 and Y2O3) buffer layer inserted between the ALD-HfO2 and MoS2 channel in order to achieve conformal HfO2/MoS2 interfaces. Utilizing the above interface engineering of MoS2/Y2O3/HfO2 stack, HfO2 dielectric thickness is further reduced down to 9 nm. Exploiting these enhanced gate stack dielectrics, we attain the highest saturation current (526 μA/μm at 0.4 μm channel length) of any MoS2 transistor reported to date, which is comparable to the same scaled state-of-the-art Si MOSFETs. At the same time, these devices also exhibit near-ideal sub-threshold slope (SS = 65 mV/decade). Furthermore, the versatility of this interface engineering technique is further illustrated with the construction of high-performance MoS2 integrated circuits such as inverters with a large voltage gain of 16, making them attractive for the incorporation into digital components. 

In recent years, due to the intriguing electrical and optical characteristics, two dimensional layered transition metal dichalcogenides such as MoS2 have attracted tremendous research attention. In a distinct contrast to the bandgap issue of graphene, MoS2 is semiconducting with a satisfied thickness-dependent bandgap of 1.2 to 1.8 eV, which can enable lots of fascinating device applications. However, until now, majority of the efforts have been focused on the integration of MoS2 devices in the back- or dual-gated geometry due to the difficulty of compact and conformal top-gated dielectric deposition directly onto the 2-D channel for the realization of high-performance top-gated FETs. In this regard, interface or dielectric engineering is an important step towards the practical implementation of MoS2 devices with the optimized performance.

In this work, we explore the case of interface engineering further by utilizing an ultrathin metal oxide (MgO, Al2O3 and Y2O3) buffer layer inserted between the ALD-HfO2 and MoS2 channel in order to achieve conformal HfO2/MoS2 interfaces. Utilizing the above interface engineering of MoS2/Y2O3/HfO2 stack, HfO2 dielectric thickness is further reduced down to 9 nm. Exploiting these enhanced gate stack dielectrics, we attain the highest saturation current (526 μA/μm at 0.4 μm channel length) of any MoS2 transistor reported to date, which is comparable to the same scaled state-of-the-art Si MOSFETs. At the same time, these devices also exhibit near-ideal sub-threshold slope (SS = 65 mV/decade). Furthermore, the versatility of this interface engineering technique is further illustrated with the construction of high-performance MoS2 integrated circuits such as inverters with a large voltage gain of 16, making them attractive for the incorporation into digital components.